1 /*
2  * drm_irq.c IRQ and vblank support
3  *
4  * \author Rickard E. (Rik) Faith <faith@valinux.com>
5  * \author Gareth Hughes <gareth@valinux.com>
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a
8  * copy of this software and associated documentation files (the "Software"),
9  * to deal in the Software without restriction, including without limitation
10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11  * and/or sell copies of the Software, and to permit persons to whom the
12  * Software is furnished to do so, subject to the following conditions:
13  *
14  * The above copyright notice and this permission notice (including the next
15  * paragraph) shall be included in all copies or substantial portions of the
16  * Software.
17  *
18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
21  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
22  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
23  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24  * OTHER DEALINGS IN THE SOFTWARE.
25  */
26 
27 #include <linux/export.h>
28 #include <linux/kthread.h>
29 #include <linux/moduleparam.h>
30 
31 #include <drm/drm_crtc.h>
32 #include <drm/drm_drv.h>
33 #include <drm/drm_framebuffer.h>
34 #include <drm/drm_managed.h>
35 #include <drm/drm_modeset_helper_vtables.h>
36 #include <drm/drm_print.h>
37 #include <drm/drm_vblank.h>
38 
39 #include "drm_internal.h"
40 #include "drm_trace.h"
41 
42 /**
43  * DOC: vblank handling
44  *
45  * From the computer's perspective, every time the monitor displays
46  * a new frame the scanout engine has "scanned out" the display image
47  * from top to bottom, one row of pixels at a time. The current row
48  * of pixels is referred to as the current scanline.
49  *
50  * In addition to the display's visible area, there's usually a couple of
51  * extra scanlines which aren't actually displayed on the screen.
52  * These extra scanlines don't contain image data and are occasionally used
53  * for features like audio and infoframes. The region made up of these
54  * scanlines is referred to as the vertical blanking region, or vblank for
55  * short.
56  *
57  * For historical reference, the vertical blanking period was designed to
58  * give the electron gun (on CRTs) enough time to move back to the top of
59  * the screen to start scanning out the next frame. Similar for horizontal
60  * blanking periods. They were designed to give the electron gun enough
61  * time to move back to the other side of the screen to start scanning the
62  * next scanline.
63  *
64  * ::
65  *
66  *
67  *    physical →   ⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽
68  *    top of      |                                        |
69  *    display     |                                        |
70  *                |               New frame                |
71  *                |                                        |
72  *                |↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓|
73  *                |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| ← Scanline,
74  *                |↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓|   updates the
75  *                |                                        |   frame as it
76  *                |                                        |   travels down
77  *                |                                        |   ("scan out")
78  *                |               Old frame                |
79  *                |                                        |
80  *                |                                        |
81  *                |                                        |
82  *                |                                        |   physical
83  *                |                                        |   bottom of
84  *    vertical    |⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽| ← display
85  *    blanking    ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
86  *    region   →  ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
87  *                ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
88  *    start of →   ⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽
89  *    new frame
90  *
91  * "Physical top of display" is the reference point for the high-precision/
92  * corrected timestamp.
93  *
94  * On a lot of display hardware, programming needs to take effect during the
95  * vertical blanking period so that settings like gamma, the image buffer
96  * buffer to be scanned out, etc. can safely be changed without showing
97  * any visual artifacts on the screen. In some unforgiving hardware, some of
98  * this programming has to both start and end in the same vblank. To help
99  * with the timing of the hardware programming, an interrupt is usually
100  * available to notify the driver when it can start the updating of registers.
101  * The interrupt is in this context named the vblank interrupt.
102  *
103  * The vblank interrupt may be fired at different points depending on the
104  * hardware. Some hardware implementations will fire the interrupt when the
105  * new frame start, other implementations will fire the interrupt at different
106  * points in time.
107  *
108  * Vertical blanking plays a major role in graphics rendering. To achieve
109  * tear-free display, users must synchronize page flips and/or rendering to
110  * vertical blanking. The DRM API offers ioctls to perform page flips
111  * synchronized to vertical blanking and wait for vertical blanking.
112  *
113  * The DRM core handles most of the vertical blanking management logic, which
114  * involves filtering out spurious interrupts, keeping race-free blanking
115  * counters, coping with counter wrap-around and resets and keeping use counts.
116  * It relies on the driver to generate vertical blanking interrupts and
117  * optionally provide a hardware vertical blanking counter.
118  *
119  * Drivers must initialize the vertical blanking handling core with a call to
120  * drm_vblank_init(). Minimally, a driver needs to implement
121  * &drm_crtc_funcs.enable_vblank and &drm_crtc_funcs.disable_vblank plus call
122  * drm_crtc_handle_vblank() in its vblank interrupt handler for working vblank
123  * support.
124  *
125  * Vertical blanking interrupts can be enabled by the DRM core or by drivers
126  * themselves (for instance to handle page flipping operations).  The DRM core
127  * maintains a vertical blanking use count to ensure that the interrupts are not
128  * disabled while a user still needs them. To increment the use count, drivers
129  * call drm_crtc_vblank_get() and release the vblank reference again with
130  * drm_crtc_vblank_put(). In between these two calls vblank interrupts are
131  * guaranteed to be enabled.
132  *
133  * On many hardware disabling the vblank interrupt cannot be done in a race-free
134  * manner, see &drm_driver.vblank_disable_immediate and
135  * &drm_driver.max_vblank_count. In that case the vblank core only disables the
136  * vblanks after a timer has expired, which can be configured through the
137  * ``vblankoffdelay`` module parameter.
138  *
139  * Drivers for hardware without support for vertical-blanking interrupts
140  * must not call drm_vblank_init(). For such drivers, atomic helpers will
141  * automatically generate fake vblank events as part of the display update.
142  * This functionality also can be controlled by the driver by enabling and
143  * disabling struct drm_crtc_state.no_vblank.
144  */
145 
146 /* Retry timestamp calculation up to 3 times to satisfy
147  * drm_timestamp_precision before giving up.
148  */
149 #define DRM_TIMESTAMP_MAXRETRIES 3
150 
151 /* Threshold in nanoseconds for detection of redundant
152  * vblank irq in drm_handle_vblank(). 1 msec should be ok.
153  */
154 #define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000
155 
156 static bool
157 drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
158 			  ktime_t *tvblank, bool in_vblank_irq);
159 
160 static unsigned int drm_timestamp_precision = 20;  /* Default to 20 usecs. */
161 
162 static int drm_vblank_offdelay = 5000;    /* Default to 5000 msecs. */
163 
164 module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
165 module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
166 MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs] (0: never disable, <0: disable immediately)");
167 MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
168 
store_vblank(struct drm_device * dev,unsigned int pipe,u32 vblank_count_inc,ktime_t t_vblank,u32 last)169 static void store_vblank(struct drm_device *dev, unsigned int pipe,
170 			 u32 vblank_count_inc,
171 			 ktime_t t_vblank, u32 last)
172 {
173 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
174 
175 	assert_spin_locked(&dev->vblank_time_lock);
176 
177 	vblank->last = last;
178 
179 	write_seqlock(&vblank->seqlock);
180 	vblank->time = t_vblank;
181 	atomic64_add(vblank_count_inc, &vblank->count);
182 	write_sequnlock(&vblank->seqlock);
183 }
184 
drm_max_vblank_count(struct drm_device * dev,unsigned int pipe)185 static u32 drm_max_vblank_count(struct drm_device *dev, unsigned int pipe)
186 {
187 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
188 
189 	return vblank->max_vblank_count ?: dev->max_vblank_count;
190 }
191 
192 /*
193  * "No hw counter" fallback implementation of .get_vblank_counter() hook,
194  * if there is no usable hardware frame counter available.
195  */
drm_vblank_no_hw_counter(struct drm_device * dev,unsigned int pipe)196 static u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe)
197 {
198 	drm_WARN_ON_ONCE(dev, drm_max_vblank_count(dev, pipe) != 0);
199 	return 0;
200 }
201 
__get_vblank_counter(struct drm_device * dev,unsigned int pipe)202 static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe)
203 {
204 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
205 		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
206 
207 		if (drm_WARN_ON(dev, !crtc))
208 			return 0;
209 
210 		if (crtc->funcs->get_vblank_counter)
211 			return crtc->funcs->get_vblank_counter(crtc);
212 	}
213 #ifdef CONFIG_DRM_LEGACY
214 	else if (dev->driver->get_vblank_counter) {
215 		return dev->driver->get_vblank_counter(dev, pipe);
216 	}
217 #endif
218 
219 	return drm_vblank_no_hw_counter(dev, pipe);
220 }
221 
222 /*
223  * Reset the stored timestamp for the current vblank count to correspond
224  * to the last vblank occurred.
225  *
226  * Only to be called from drm_crtc_vblank_on().
227  *
228  * Note: caller must hold &drm_device.vbl_lock since this reads & writes
229  * device vblank fields.
230  */
drm_reset_vblank_timestamp(struct drm_device * dev,unsigned int pipe)231 static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe)
232 {
233 	u32 cur_vblank;
234 	bool rc;
235 	ktime_t t_vblank;
236 	int count = DRM_TIMESTAMP_MAXRETRIES;
237 
238 	spin_lock(&dev->vblank_time_lock);
239 
240 	/*
241 	 * sample the current counter to avoid random jumps
242 	 * when drm_vblank_enable() applies the diff
243 	 */
244 	do {
245 		cur_vblank = __get_vblank_counter(dev, pipe);
246 		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, false);
247 	} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
248 
249 	/*
250 	 * Only reinitialize corresponding vblank timestamp if high-precision query
251 	 * available and didn't fail. Otherwise reinitialize delayed at next vblank
252 	 * interrupt and assign 0 for now, to mark the vblanktimestamp as invalid.
253 	 */
254 	if (!rc)
255 		t_vblank = 0;
256 
257 	/*
258 	 * +1 to make sure user will never see the same
259 	 * vblank counter value before and after a modeset
260 	 */
261 	store_vblank(dev, pipe, 1, t_vblank, cur_vblank);
262 
263 	spin_unlock(&dev->vblank_time_lock);
264 }
265 
266 /*
267  * Call back into the driver to update the appropriate vblank counter
268  * (specified by @pipe).  Deal with wraparound, if it occurred, and
269  * update the last read value so we can deal with wraparound on the next
270  * call if necessary.
271  *
272  * Only necessary when going from off->on, to account for frames we
273  * didn't get an interrupt for.
274  *
275  * Note: caller must hold &drm_device.vbl_lock since this reads & writes
276  * device vblank fields.
277  */
drm_update_vblank_count(struct drm_device * dev,unsigned int pipe,bool in_vblank_irq)278 static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
279 				    bool in_vblank_irq)
280 {
281 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
282 	u32 cur_vblank, diff;
283 	bool rc;
284 	ktime_t t_vblank;
285 	int count = DRM_TIMESTAMP_MAXRETRIES;
286 	int framedur_ns = vblank->framedur_ns;
287 	u32 max_vblank_count = drm_max_vblank_count(dev, pipe);
288 
289 	/*
290 	 * Interrupts were disabled prior to this call, so deal with counter
291 	 * wrap if needed.
292 	 * NOTE!  It's possible we lost a full dev->max_vblank_count + 1 events
293 	 * here if the register is small or we had vblank interrupts off for
294 	 * a long time.
295 	 *
296 	 * We repeat the hardware vblank counter & timestamp query until
297 	 * we get consistent results. This to prevent races between gpu
298 	 * updating its hardware counter while we are retrieving the
299 	 * corresponding vblank timestamp.
300 	 */
301 	do {
302 		cur_vblank = __get_vblank_counter(dev, pipe);
303 		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, in_vblank_irq);
304 	} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
305 
306 	if (max_vblank_count) {
307 		/* trust the hw counter when it's around */
308 		diff = (cur_vblank - vblank->last) & max_vblank_count;
309 	} else if (rc && framedur_ns) {
310 		u64 diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time));
311 
312 		/*
313 		 * Figure out how many vblanks we've missed based
314 		 * on the difference in the timestamps and the
315 		 * frame/field duration.
316 		 */
317 
318 		drm_dbg_vbl(dev, "crtc %u: Calculating number of vblanks."
319 			    " diff_ns = %lld, framedur_ns = %d)\n",
320 			    pipe, (long long)diff_ns, framedur_ns);
321 
322 		diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
323 
324 		if (diff == 0 && in_vblank_irq)
325 			drm_dbg_vbl(dev, "crtc %u: Redundant vblirq ignored\n",
326 				    pipe);
327 	} else {
328 		/* some kind of default for drivers w/o accurate vbl timestamping */
329 		diff = in_vblank_irq ? 1 : 0;
330 	}
331 
332 	/*
333 	 * Within a drm_vblank_pre_modeset - drm_vblank_post_modeset
334 	 * interval? If so then vblank irqs keep running and it will likely
335 	 * happen that the hardware vblank counter is not trustworthy as it
336 	 * might reset at some point in that interval and vblank timestamps
337 	 * are not trustworthy either in that interval. Iow. this can result
338 	 * in a bogus diff >> 1 which must be avoided as it would cause
339 	 * random large forward jumps of the software vblank counter.
340 	 */
341 	if (diff > 1 && (vblank->inmodeset & 0x2)) {
342 		drm_dbg_vbl(dev,
343 			    "clamping vblank bump to 1 on crtc %u: diffr=%u"
344 			    " due to pre-modeset.\n", pipe, diff);
345 		diff = 1;
346 	}
347 
348 	drm_dbg_vbl(dev, "updating vblank count on crtc %u:"
349 		    " current=%llu, diff=%u, hw=%u hw_last=%u\n",
350 		    pipe, (unsigned long long)atomic64_read(&vblank->count),
351 		    diff, cur_vblank, vblank->last);
352 
353 	if (diff == 0) {
354 		drm_WARN_ON_ONCE(dev, cur_vblank != vblank->last);
355 		return;
356 	}
357 
358 	/*
359 	 * Only reinitialize corresponding vblank timestamp if high-precision query
360 	 * available and didn't fail, or we were called from the vblank interrupt.
361 	 * Otherwise reinitialize delayed at next vblank interrupt and assign 0
362 	 * for now, to mark the vblanktimestamp as invalid.
363 	 */
364 	if (!rc && !in_vblank_irq)
365 		t_vblank = 0;
366 
367 	store_vblank(dev, pipe, diff, t_vblank, cur_vblank);
368 }
369 
drm_vblank_count(struct drm_device * dev,unsigned int pipe)370 u64 drm_vblank_count(struct drm_device *dev, unsigned int pipe)
371 {
372 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
373 	u64 count;
374 
375 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
376 		return 0;
377 
378 	count = atomic64_read(&vblank->count);
379 
380 	/*
381 	 * This read barrier corresponds to the implicit write barrier of the
382 	 * write seqlock in store_vblank(). Note that this is the only place
383 	 * where we need an explicit barrier, since all other access goes
384 	 * through drm_vblank_count_and_time(), which already has the required
385 	 * read barrier curtesy of the read seqlock.
386 	 */
387 	smp_rmb();
388 
389 	return count;
390 }
391 
392 /**
393  * drm_crtc_accurate_vblank_count - retrieve the master vblank counter
394  * @crtc: which counter to retrieve
395  *
396  * This function is similar to drm_crtc_vblank_count() but this function
397  * interpolates to handle a race with vblank interrupts using the high precision
398  * timestamping support.
399  *
400  * This is mostly useful for hardware that can obtain the scanout position, but
401  * doesn't have a hardware frame counter.
402  */
drm_crtc_accurate_vblank_count(struct drm_crtc * crtc)403 u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc)
404 {
405 	struct drm_device *dev = crtc->dev;
406 	unsigned int pipe = drm_crtc_index(crtc);
407 	u64 vblank;
408 	unsigned long flags;
409 
410 	drm_WARN_ONCE(dev, drm_debug_enabled(DRM_UT_VBL) &&
411 		      !crtc->funcs->get_vblank_timestamp,
412 		      "This function requires support for accurate vblank timestamps.");
413 
414 	spin_lock_irqsave(&dev->vblank_time_lock, flags);
415 
416 	drm_update_vblank_count(dev, pipe, false);
417 	vblank = drm_vblank_count(dev, pipe);
418 
419 	spin_unlock_irqrestore(&dev->vblank_time_lock, flags);
420 
421 	return vblank;
422 }
423 EXPORT_SYMBOL(drm_crtc_accurate_vblank_count);
424 
__disable_vblank(struct drm_device * dev,unsigned int pipe)425 static void __disable_vblank(struct drm_device *dev, unsigned int pipe)
426 {
427 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
428 		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
429 
430 		if (drm_WARN_ON(dev, !crtc))
431 			return;
432 
433 		if (crtc->funcs->disable_vblank)
434 			crtc->funcs->disable_vblank(crtc);
435 	}
436 #ifdef CONFIG_DRM_LEGACY
437 	else {
438 		dev->driver->disable_vblank(dev, pipe);
439 	}
440 #endif
441 }
442 
443 /*
444  * Disable vblank irq's on crtc, make sure that last vblank count
445  * of hardware and corresponding consistent software vblank counter
446  * are preserved, even if there are any spurious vblank irq's after
447  * disable.
448  */
drm_vblank_disable_and_save(struct drm_device * dev,unsigned int pipe)449 void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
450 {
451 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
452 	unsigned long irqflags;
453 
454 	assert_spin_locked(&dev->vbl_lock);
455 
456 	/* Prevent vblank irq processing while disabling vblank irqs,
457 	 * so no updates of timestamps or count can happen after we've
458 	 * disabled. Needed to prevent races in case of delayed irq's.
459 	 */
460 	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
461 
462 	/*
463 	 * Update vblank count and disable vblank interrupts only if the
464 	 * interrupts were enabled. This avoids calling the ->disable_vblank()
465 	 * operation in atomic context with the hardware potentially runtime
466 	 * suspended.
467 	 */
468 	if (!vblank->enabled)
469 		goto out;
470 
471 	/*
472 	 * Update the count and timestamp to maintain the
473 	 * appearance that the counter has been ticking all along until
474 	 * this time. This makes the count account for the entire time
475 	 * between drm_crtc_vblank_on() and drm_crtc_vblank_off().
476 	 */
477 	drm_update_vblank_count(dev, pipe, false);
478 	__disable_vblank(dev, pipe);
479 	vblank->enabled = false;
480 
481 out:
482 	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
483 }
484 
vblank_disable_fn(struct timer_list * t)485 static void vblank_disable_fn(struct timer_list *t)
486 {
487 	struct drm_vblank_crtc *vblank = from_timer(vblank, t, disable_timer);
488 	struct drm_device *dev = vblank->dev;
489 	unsigned int pipe = vblank->pipe;
490 	unsigned long irqflags;
491 
492 	spin_lock_irqsave(&dev->vbl_lock, irqflags);
493 	if (atomic_read(&vblank->refcount) == 0 && vblank->enabled) {
494 		drm_dbg_core(dev, "disabling vblank on crtc %u\n", pipe);
495 		drm_vblank_disable_and_save(dev, pipe);
496 	}
497 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
498 }
499 
drm_vblank_init_release(struct drm_device * dev,void * ptr)500 static void drm_vblank_init_release(struct drm_device *dev, void *ptr)
501 {
502 	struct drm_vblank_crtc *vblank = ptr;
503 
504 	drm_WARN_ON(dev, READ_ONCE(vblank->enabled) &&
505 		    drm_core_check_feature(dev, DRIVER_MODESET));
506 
507 	drm_vblank_destroy_worker(vblank);
508 	del_timer_sync(&vblank->disable_timer);
509 }
510 
511 /**
512  * drm_vblank_init - initialize vblank support
513  * @dev: DRM device
514  * @num_crtcs: number of CRTCs supported by @dev
515  *
516  * This function initializes vblank support for @num_crtcs display pipelines.
517  * Cleanup is handled automatically through a cleanup function added with
518  * drmm_add_action_or_reset().
519  *
520  * Returns:
521  * Zero on success or a negative error code on failure.
522  */
drm_vblank_init(struct drm_device * dev,unsigned int num_crtcs)523 int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
524 {
525 	int ret;
526 	unsigned int i;
527 
528 	spin_lock_init(&dev->vbl_lock);
529 	spin_lock_init(&dev->vblank_time_lock);
530 
531 	dev->vblank = drmm_kcalloc(dev, num_crtcs, sizeof(*dev->vblank), GFP_KERNEL);
532 	if (!dev->vblank)
533 		return -ENOMEM;
534 
535 	dev->num_crtcs = num_crtcs;
536 
537 	for (i = 0; i < num_crtcs; i++) {
538 		struct drm_vblank_crtc *vblank = &dev->vblank[i];
539 
540 		vblank->dev = dev;
541 		vblank->pipe = i;
542 		init_waitqueue_head(&vblank->queue);
543 		timer_setup(&vblank->disable_timer, vblank_disable_fn, 0);
544 		seqlock_init(&vblank->seqlock);
545 
546 		ret = drmm_add_action_or_reset(dev, drm_vblank_init_release,
547 					       vblank);
548 		if (ret)
549 			return ret;
550 
551 		ret = drm_vblank_worker_init(vblank);
552 		if (ret)
553 			return ret;
554 	}
555 
556 	return 0;
557 }
558 EXPORT_SYMBOL(drm_vblank_init);
559 
560 /**
561  * drm_dev_has_vblank - test if vblanking has been initialized for
562  *                      a device
563  * @dev: the device
564  *
565  * Drivers may call this function to test if vblank support is
566  * initialized for a device. For most hardware this means that vblanking
567  * can also be enabled.
568  *
569  * Atomic helpers use this function to initialize
570  * &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset().
571  *
572  * Returns:
573  * True if vblanking has been initialized for the given device, false
574  * otherwise.
575  */
drm_dev_has_vblank(const struct drm_device * dev)576 bool drm_dev_has_vblank(const struct drm_device *dev)
577 {
578 	return dev->num_crtcs != 0;
579 }
580 EXPORT_SYMBOL(drm_dev_has_vblank);
581 
582 /**
583  * drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC
584  * @crtc: which CRTC's vblank waitqueue to retrieve
585  *
586  * This function returns a pointer to the vblank waitqueue for the CRTC.
587  * Drivers can use this to implement vblank waits using wait_event() and related
588  * functions.
589  */
drm_crtc_vblank_waitqueue(struct drm_crtc * crtc)590 wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc)
591 {
592 	return &crtc->dev->vblank[drm_crtc_index(crtc)].queue;
593 }
594 EXPORT_SYMBOL(drm_crtc_vblank_waitqueue);
595 
596 
597 /**
598  * drm_calc_timestamping_constants - calculate vblank timestamp constants
599  * @crtc: drm_crtc whose timestamp constants should be updated.
600  * @mode: display mode containing the scanout timings
601  *
602  * Calculate and store various constants which are later needed by vblank and
603  * swap-completion timestamping, e.g, by
604  * drm_crtc_vblank_helper_get_vblank_timestamp(). They are derived from
605  * CRTC's true scanout timing, so they take things like panel scaling or
606  * other adjustments into account.
607  */
drm_calc_timestamping_constants(struct drm_crtc * crtc,const struct drm_display_mode * mode)608 void drm_calc_timestamping_constants(struct drm_crtc *crtc,
609 				     const struct drm_display_mode *mode)
610 {
611 	struct drm_device *dev = crtc->dev;
612 	unsigned int pipe = drm_crtc_index(crtc);
613 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
614 	int linedur_ns = 0, framedur_ns = 0;
615 	int dotclock = mode->crtc_clock;
616 
617 	if (!drm_dev_has_vblank(dev))
618 		return;
619 
620 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
621 		return;
622 
623 	/* Valid dotclock? */
624 	if (dotclock > 0) {
625 		int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
626 
627 		/*
628 		 * Convert scanline length in pixels and video
629 		 * dot clock to line duration and frame duration
630 		 * in nanoseconds:
631 		 */
632 		linedur_ns  = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);
633 		framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);
634 
635 		/*
636 		 * Fields of interlaced scanout modes are only half a frame duration.
637 		 */
638 		if (mode->flags & DRM_MODE_FLAG_INTERLACE)
639 			framedur_ns /= 2;
640 	} else {
641 		drm_err(dev, "crtc %u: Can't calculate constants, dotclock = 0!\n",
642 			crtc->base.id);
643 	}
644 
645 	vblank->linedur_ns  = linedur_ns;
646 	vblank->framedur_ns = framedur_ns;
647 	drm_mode_copy(&vblank->hwmode, mode);
648 
649 	drm_dbg_core(dev,
650 		     "crtc %u: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
651 		     crtc->base.id, mode->crtc_htotal,
652 		     mode->crtc_vtotal, mode->crtc_vdisplay);
653 	drm_dbg_core(dev, "crtc %u: clock %d kHz framedur %d linedur %d\n",
654 		     crtc->base.id, dotclock, framedur_ns, linedur_ns);
655 }
656 EXPORT_SYMBOL(drm_calc_timestamping_constants);
657 
658 /**
659  * drm_crtc_vblank_helper_get_vblank_timestamp_internal - precise vblank
660  *                                                        timestamp helper
661  * @crtc: CRTC whose vblank timestamp to retrieve
662  * @max_error: Desired maximum allowable error in timestamps (nanosecs)
663  *             On return contains true maximum error of timestamp
664  * @vblank_time: Pointer to time which should receive the timestamp
665  * @in_vblank_irq:
666  *     True when called from drm_crtc_handle_vblank().  Some drivers
667  *     need to apply some workarounds for gpu-specific vblank irq quirks
668  *     if flag is set.
669  * @get_scanout_position:
670  *     Callback function to retrieve the scanout position. See
671  *     @struct drm_crtc_helper_funcs.get_scanout_position.
672  *
673  * Implements calculation of exact vblank timestamps from given drm_display_mode
674  * timings and current video scanout position of a CRTC.
675  *
676  * The current implementation only handles standard video modes. For double scan
677  * and interlaced modes the driver is supposed to adjust the hardware mode
678  * (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to
679  * match the scanout position reported.
680  *
681  * Note that atomic drivers must call drm_calc_timestamping_constants() before
682  * enabling a CRTC. The atomic helpers already take care of that in
683  * drm_atomic_helper_calc_timestamping_constants().
684  *
685  * Returns:
686  *
687  * Returns true on success, and false on failure, i.e. when no accurate
688  * timestamp could be acquired.
689  */
690 bool
drm_crtc_vblank_helper_get_vblank_timestamp_internal(struct drm_crtc * crtc,int * max_error,ktime_t * vblank_time,bool in_vblank_irq,drm_vblank_get_scanout_position_func get_scanout_position)691 drm_crtc_vblank_helper_get_vblank_timestamp_internal(
692 	struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time,
693 	bool in_vblank_irq,
694 	drm_vblank_get_scanout_position_func get_scanout_position)
695 {
696 	struct drm_device *dev = crtc->dev;
697 	unsigned int pipe = crtc->index;
698 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
699 	struct timespec64 ts_etime, ts_vblank_time;
700 	ktime_t stime, etime;
701 	bool vbl_status;
702 	const struct drm_display_mode *mode;
703 	int vpos, hpos, i;
704 	int delta_ns, duration_ns;
705 
706 	if (pipe >= dev->num_crtcs) {
707 		drm_err(dev, "Invalid crtc %u\n", pipe);
708 		return false;
709 	}
710 
711 	/* Scanout position query not supported? Should not happen. */
712 	if (!get_scanout_position) {
713 		drm_err(dev, "Called from CRTC w/o get_scanout_position()!?\n");
714 		return false;
715 	}
716 
717 	if (drm_drv_uses_atomic_modeset(dev))
718 		mode = &vblank->hwmode;
719 	else
720 		mode = &crtc->hwmode;
721 
722 	/* If mode timing undefined, just return as no-op:
723 	 * Happens during initial modesetting of a crtc.
724 	 */
725 	if (mode->crtc_clock == 0) {
726 		drm_dbg_core(dev, "crtc %u: Noop due to uninitialized mode.\n",
727 			     pipe);
728 		drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev));
729 		return false;
730 	}
731 
732 	/* Get current scanout position with system timestamp.
733 	 * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
734 	 * if single query takes longer than max_error nanoseconds.
735 	 *
736 	 * This guarantees a tight bound on maximum error if
737 	 * code gets preempted or delayed for some reason.
738 	 */
739 	for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
740 		/*
741 		 * Get vertical and horizontal scanout position vpos, hpos,
742 		 * and bounding timestamps stime, etime, pre/post query.
743 		 */
744 		vbl_status = get_scanout_position(crtc, in_vblank_irq,
745 						  &vpos, &hpos,
746 						  &stime, &etime,
747 						  mode);
748 
749 		/* Return as no-op if scanout query unsupported or failed. */
750 		if (!vbl_status) {
751 			drm_dbg_core(dev,
752 				     "crtc %u : scanoutpos query failed.\n",
753 				     pipe);
754 			return false;
755 		}
756 
757 		/* Compute uncertainty in timestamp of scanout position query. */
758 		duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
759 
760 		/* Accept result with <  max_error nsecs timing uncertainty. */
761 		if (duration_ns <= *max_error)
762 			break;
763 	}
764 
765 	/* Noisy system timing? */
766 	if (i == DRM_TIMESTAMP_MAXRETRIES) {
767 		drm_dbg_core(dev,
768 			     "crtc %u: Noisy timestamp %d us > %d us [%d reps].\n",
769 			     pipe, duration_ns / 1000, *max_error / 1000, i);
770 	}
771 
772 	/* Return upper bound of timestamp precision error. */
773 	*max_error = duration_ns;
774 
775 	/* Convert scanout position into elapsed time at raw_time query
776 	 * since start of scanout at first display scanline. delta_ns
777 	 * can be negative if start of scanout hasn't happened yet.
778 	 */
779 	delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),
780 			   mode->crtc_clock);
781 
782 	/* Subtract time delta from raw timestamp to get final
783 	 * vblank_time timestamp for end of vblank.
784 	 */
785 	*vblank_time = ktime_sub_ns(etime, delta_ns);
786 
787 	if (!drm_debug_enabled(DRM_UT_VBL))
788 		return true;
789 
790 	ts_etime = ktime_to_timespec64(etime);
791 	ts_vblank_time = ktime_to_timespec64(*vblank_time);
792 
793 	drm_dbg_vbl(dev,
794 		    "crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n",
795 		    pipe, hpos, vpos,
796 		    (u64)ts_etime.tv_sec, ts_etime.tv_nsec / 1000,
797 		    (u64)ts_vblank_time.tv_sec, ts_vblank_time.tv_nsec / 1000,
798 		    duration_ns / 1000, i);
799 
800 	return true;
801 }
802 EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp_internal);
803 
804 /**
805  * drm_crtc_vblank_helper_get_vblank_timestamp - precise vblank timestamp
806  *                                               helper
807  * @crtc: CRTC whose vblank timestamp to retrieve
808  * @max_error: Desired maximum allowable error in timestamps (nanosecs)
809  *             On return contains true maximum error of timestamp
810  * @vblank_time: Pointer to time which should receive the timestamp
811  * @in_vblank_irq:
812  *     True when called from drm_crtc_handle_vblank().  Some drivers
813  *     need to apply some workarounds for gpu-specific vblank irq quirks
814  *     if flag is set.
815  *
816  * Implements calculation of exact vblank timestamps from given drm_display_mode
817  * timings and current video scanout position of a CRTC. This can be directly
818  * used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms
819  * driver if &drm_crtc_helper_funcs.get_scanout_position is implemented.
820  *
821  * The current implementation only handles standard video modes. For double scan
822  * and interlaced modes the driver is supposed to adjust the hardware mode
823  * (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to
824  * match the scanout position reported.
825  *
826  * Note that atomic drivers must call drm_calc_timestamping_constants() before
827  * enabling a CRTC. The atomic helpers already take care of that in
828  * drm_atomic_helper_calc_timestamping_constants().
829  *
830  * Returns:
831  *
832  * Returns true on success, and false on failure, i.e. when no accurate
833  * timestamp could be acquired.
834  */
drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc * crtc,int * max_error,ktime_t * vblank_time,bool in_vblank_irq)835 bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
836 						 int *max_error,
837 						 ktime_t *vblank_time,
838 						 bool in_vblank_irq)
839 {
840 	return drm_crtc_vblank_helper_get_vblank_timestamp_internal(
841 		crtc, max_error, vblank_time, in_vblank_irq,
842 		crtc->helper_private->get_scanout_position);
843 }
844 EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
845 
846 /**
847  * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
848  *                             vblank interval
849  * @dev: DRM device
850  * @pipe: index of CRTC whose vblank timestamp to retrieve
851  * @tvblank: Pointer to target time which should receive the timestamp
852  * @in_vblank_irq:
853  *     True when called from drm_crtc_handle_vblank().  Some drivers
854  *     need to apply some workarounds for gpu-specific vblank irq quirks
855  *     if flag is set.
856  *
857  * Fetches the system timestamp corresponding to the time of the most recent
858  * vblank interval on specified CRTC. May call into kms-driver to
859  * compute the timestamp with a high-precision GPU specific method.
860  *
861  * Returns zero if timestamp originates from uncorrected do_gettimeofday()
862  * call, i.e., it isn't very precisely locked to the true vblank.
863  *
864  * Returns:
865  * True if timestamp is considered to be very precise, false otherwise.
866  */
867 static bool
drm_get_last_vbltimestamp(struct drm_device * dev,unsigned int pipe,ktime_t * tvblank,bool in_vblank_irq)868 drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
869 			  ktime_t *tvblank, bool in_vblank_irq)
870 {
871 	struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
872 	bool ret = false;
873 
874 	/* Define requested maximum error on timestamps (nanoseconds). */
875 	int max_error = (int) drm_timestamp_precision * 1000;
876 
877 	/* Query driver if possible and precision timestamping enabled. */
878 	if (crtc && crtc->funcs->get_vblank_timestamp && max_error > 0) {
879 		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
880 
881 		ret = crtc->funcs->get_vblank_timestamp(crtc, &max_error,
882 							tvblank, in_vblank_irq);
883 	}
884 
885 	/* GPU high precision timestamp query unsupported or failed.
886 	 * Return current monotonic/gettimeofday timestamp as best estimate.
887 	 */
888 	if (!ret)
889 		*tvblank = ktime_get();
890 
891 	return ret;
892 }
893 
894 /**
895  * drm_crtc_vblank_count - retrieve "cooked" vblank counter value
896  * @crtc: which counter to retrieve
897  *
898  * Fetches the "cooked" vblank count value that represents the number of
899  * vblank events since the system was booted, including lost events due to
900  * modesetting activity. Note that this timer isn't correct against a racing
901  * vblank interrupt (since it only reports the software vblank counter), see
902  * drm_crtc_accurate_vblank_count() for such use-cases.
903  *
904  * Note that for a given vblank counter value drm_crtc_handle_vblank()
905  * and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
906  * provide a barrier: Any writes done before calling
907  * drm_crtc_handle_vblank() will be visible to callers of the later
908  * functions, if the vblank count is the same or a later one.
909  *
910  * See also &drm_vblank_crtc.count.
911  *
912  * Returns:
913  * The software vblank counter.
914  */
drm_crtc_vblank_count(struct drm_crtc * crtc)915 u64 drm_crtc_vblank_count(struct drm_crtc *crtc)
916 {
917 	return drm_vblank_count(crtc->dev, drm_crtc_index(crtc));
918 }
919 EXPORT_SYMBOL(drm_crtc_vblank_count);
920 
921 /**
922  * drm_vblank_count_and_time - retrieve "cooked" vblank counter value and the
923  *     system timestamp corresponding to that vblank counter value.
924  * @dev: DRM device
925  * @pipe: index of CRTC whose counter to retrieve
926  * @vblanktime: Pointer to ktime_t to receive the vblank timestamp.
927  *
928  * Fetches the "cooked" vblank count value that represents the number of
929  * vblank events since the system was booted, including lost events due to
930  * modesetting activity. Returns corresponding system timestamp of the time
931  * of the vblank interval that corresponds to the current vblank counter value.
932  *
933  * This is the legacy version of drm_crtc_vblank_count_and_time().
934  */
drm_vblank_count_and_time(struct drm_device * dev,unsigned int pipe,ktime_t * vblanktime)935 static u64 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe,
936 				     ktime_t *vblanktime)
937 {
938 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
939 	u64 vblank_count;
940 	unsigned int seq;
941 
942 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs)) {
943 		*vblanktime = 0;
944 		return 0;
945 	}
946 
947 	do {
948 		seq = read_seqbegin(&vblank->seqlock);
949 		vblank_count = atomic64_read(&vblank->count);
950 		*vblanktime = vblank->time;
951 	} while (read_seqretry(&vblank->seqlock, seq));
952 
953 	return vblank_count;
954 }
955 
956 /**
957  * drm_crtc_vblank_count_and_time - retrieve "cooked" vblank counter value
958  *     and the system timestamp corresponding to that vblank counter value
959  * @crtc: which counter to retrieve
960  * @vblanktime: Pointer to time to receive the vblank timestamp.
961  *
962  * Fetches the "cooked" vblank count value that represents the number of
963  * vblank events since the system was booted, including lost events due to
964  * modesetting activity. Returns corresponding system timestamp of the time
965  * of the vblank interval that corresponds to the current vblank counter value.
966  *
967  * Note that for a given vblank counter value drm_crtc_handle_vblank()
968  * and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
969  * provide a barrier: Any writes done before calling
970  * drm_crtc_handle_vblank() will be visible to callers of the later
971  * functions, if the vblank count is the same or a later one.
972  *
973  * See also &drm_vblank_crtc.count.
974  */
drm_crtc_vblank_count_and_time(struct drm_crtc * crtc,ktime_t * vblanktime)975 u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
976 				   ktime_t *vblanktime)
977 {
978 	return drm_vblank_count_and_time(crtc->dev, drm_crtc_index(crtc),
979 					 vblanktime);
980 }
981 EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
982 
send_vblank_event(struct drm_device * dev,struct drm_pending_vblank_event * e,u64 seq,ktime_t now)983 static void send_vblank_event(struct drm_device *dev,
984 		struct drm_pending_vblank_event *e,
985 		u64 seq, ktime_t now)
986 {
987 	struct timespec64 tv;
988 
989 	switch (e->event.base.type) {
990 	case DRM_EVENT_VBLANK:
991 	case DRM_EVENT_FLIP_COMPLETE:
992 		tv = ktime_to_timespec64(now);
993 		e->event.vbl.sequence = seq;
994 		/*
995 		 * e->event is a user space structure, with hardcoded unsigned
996 		 * 32-bit seconds/microseconds. This is safe as we always use
997 		 * monotonic timestamps since linux-4.15
998 		 */
999 		e->event.vbl.tv_sec = tv.tv_sec;
1000 		e->event.vbl.tv_usec = tv.tv_nsec / 1000;
1001 		break;
1002 	case DRM_EVENT_CRTC_SEQUENCE:
1003 		if (seq)
1004 			e->event.seq.sequence = seq;
1005 		e->event.seq.time_ns = ktime_to_ns(now);
1006 		break;
1007 	}
1008 	trace_drm_vblank_event_delivered(e->base.file_priv, e->pipe, seq);
1009 	/*
1010 	 * Use the same timestamp for any associated fence signal to avoid
1011 	 * mismatch in timestamps for vsync & fence events triggered by the
1012 	 * same HW event. Frameworks like SurfaceFlinger in Android expects the
1013 	 * retire-fence timestamp to match exactly with HW vsync as it uses it
1014 	 * for its software vsync modeling.
1015 	 */
1016 	drm_send_event_timestamp_locked(dev, &e->base, now);
1017 }
1018 
1019 /**
1020  * drm_crtc_arm_vblank_event - arm vblank event after pageflip
1021  * @crtc: the source CRTC of the vblank event
1022  * @e: the event to send
1023  *
1024  * A lot of drivers need to generate vblank events for the very next vblank
1025  * interrupt. For example when the page flip interrupt happens when the page
1026  * flip gets armed, but not when it actually executes within the next vblank
1027  * period. This helper function implements exactly the required vblank arming
1028  * behaviour.
1029  *
1030  * NOTE: Drivers using this to send out the &drm_crtc_state.event as part of an
1031  * atomic commit must ensure that the next vblank happens at exactly the same
1032  * time as the atomic commit is committed to the hardware. This function itself
1033  * does **not** protect against the next vblank interrupt racing with either this
1034  * function call or the atomic commit operation. A possible sequence could be:
1035  *
1036  * 1. Driver commits new hardware state into vblank-synchronized registers.
1037  * 2. A vblank happens, committing the hardware state. Also the corresponding
1038  *    vblank interrupt is fired off and fully processed by the interrupt
1039  *    handler.
1040  * 3. The atomic commit operation proceeds to call drm_crtc_arm_vblank_event().
1041  * 4. The event is only send out for the next vblank, which is wrong.
1042  *
1043  * An equivalent race can happen when the driver calls
1044  * drm_crtc_arm_vblank_event() before writing out the new hardware state.
1045  *
1046  * The only way to make this work safely is to prevent the vblank from firing
1047  * (and the hardware from committing anything else) until the entire atomic
1048  * commit sequence has run to completion. If the hardware does not have such a
1049  * feature (e.g. using a "go" bit), then it is unsafe to use this functions.
1050  * Instead drivers need to manually send out the event from their interrupt
1051  * handler by calling drm_crtc_send_vblank_event() and make sure that there's no
1052  * possible race with the hardware committing the atomic update.
1053  *
1054  * Caller must hold a vblank reference for the event @e acquired by a
1055  * drm_crtc_vblank_get(), which will be dropped when the next vblank arrives.
1056  */
drm_crtc_arm_vblank_event(struct drm_crtc * crtc,struct drm_pending_vblank_event * e)1057 void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
1058 			       struct drm_pending_vblank_event *e)
1059 {
1060 	struct drm_device *dev = crtc->dev;
1061 	unsigned int pipe = drm_crtc_index(crtc);
1062 
1063 	assert_spin_locked(&dev->event_lock);
1064 
1065 	e->pipe = pipe;
1066 	e->sequence = drm_crtc_accurate_vblank_count(crtc) + 1;
1067 	list_add_tail(&e->base.link, &dev->vblank_event_list);
1068 }
1069 EXPORT_SYMBOL(drm_crtc_arm_vblank_event);
1070 
1071 /**
1072  * drm_crtc_send_vblank_event - helper to send vblank event after pageflip
1073  * @crtc: the source CRTC of the vblank event
1074  * @e: the event to send
1075  *
1076  * Updates sequence # and timestamp on event for the most recently processed
1077  * vblank, and sends it to userspace.  Caller must hold event lock.
1078  *
1079  * See drm_crtc_arm_vblank_event() for a helper which can be used in certain
1080  * situation, especially to send out events for atomic commit operations.
1081  */
drm_crtc_send_vblank_event(struct drm_crtc * crtc,struct drm_pending_vblank_event * e)1082 void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
1083 				struct drm_pending_vblank_event *e)
1084 {
1085 	struct drm_device *dev = crtc->dev;
1086 	u64 seq;
1087 	unsigned int pipe = drm_crtc_index(crtc);
1088 	ktime_t now;
1089 
1090 	if (drm_dev_has_vblank(dev)) {
1091 		seq = drm_vblank_count_and_time(dev, pipe, &now);
1092 	} else {
1093 		seq = 0;
1094 
1095 		now = ktime_get();
1096 	}
1097 	e->pipe = pipe;
1098 	send_vblank_event(dev, e, seq, now);
1099 }
1100 EXPORT_SYMBOL(drm_crtc_send_vblank_event);
1101 
__enable_vblank(struct drm_device * dev,unsigned int pipe)1102 static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
1103 {
1104 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
1105 		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
1106 
1107 		if (drm_WARN_ON(dev, !crtc))
1108 			return 0;
1109 
1110 		if (crtc->funcs->enable_vblank)
1111 			return crtc->funcs->enable_vblank(crtc);
1112 	}
1113 #ifdef CONFIG_DRM_LEGACY
1114 	else if (dev->driver->enable_vblank) {
1115 		return dev->driver->enable_vblank(dev, pipe);
1116 	}
1117 #endif
1118 
1119 	return -EINVAL;
1120 }
1121 
drm_vblank_enable(struct drm_device * dev,unsigned int pipe)1122 static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
1123 {
1124 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1125 	int ret = 0;
1126 
1127 	assert_spin_locked(&dev->vbl_lock);
1128 
1129 	spin_lock(&dev->vblank_time_lock);
1130 
1131 	if (!vblank->enabled) {
1132 		/*
1133 		 * Enable vblank irqs under vblank_time_lock protection.
1134 		 * All vblank count & timestamp updates are held off
1135 		 * until we are done reinitializing master counter and
1136 		 * timestamps. Filtercode in drm_handle_vblank() will
1137 		 * prevent double-accounting of same vblank interval.
1138 		 */
1139 		ret = __enable_vblank(dev, pipe);
1140 		drm_dbg_core(dev, "enabling vblank on crtc %u, ret: %d\n",
1141 			     pipe, ret);
1142 		if (ret) {
1143 			atomic_dec(&vblank->refcount);
1144 		} else {
1145 			drm_update_vblank_count(dev, pipe, 0);
1146 			/* drm_update_vblank_count() includes a wmb so we just
1147 			 * need to ensure that the compiler emits the write
1148 			 * to mark the vblank as enabled after the call
1149 			 * to drm_update_vblank_count().
1150 			 */
1151 			WRITE_ONCE(vblank->enabled, true);
1152 		}
1153 	}
1154 
1155 	spin_unlock(&dev->vblank_time_lock);
1156 
1157 	return ret;
1158 }
1159 
drm_vblank_get(struct drm_device * dev,unsigned int pipe)1160 int drm_vblank_get(struct drm_device *dev, unsigned int pipe)
1161 {
1162 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1163 	unsigned long irqflags;
1164 	int ret = 0;
1165 
1166 	if (!drm_dev_has_vblank(dev))
1167 		return -EINVAL;
1168 
1169 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1170 		return -EINVAL;
1171 
1172 	spin_lock_irqsave(&dev->vbl_lock, irqflags);
1173 	/* Going from 0->1 means we have to enable interrupts again */
1174 	if (atomic_add_return(1, &vblank->refcount) == 1) {
1175 		ret = drm_vblank_enable(dev, pipe);
1176 	} else {
1177 		if (!vblank->enabled) {
1178 			atomic_dec(&vblank->refcount);
1179 			ret = -EINVAL;
1180 		}
1181 	}
1182 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
1183 
1184 	return ret;
1185 }
1186 
1187 /**
1188  * drm_crtc_vblank_get - get a reference count on vblank events
1189  * @crtc: which CRTC to own
1190  *
1191  * Acquire a reference count on vblank events to avoid having them disabled
1192  * while in use.
1193  *
1194  * Returns:
1195  * Zero on success or a negative error code on failure.
1196  */
drm_crtc_vblank_get(struct drm_crtc * crtc)1197 int drm_crtc_vblank_get(struct drm_crtc *crtc)
1198 {
1199 	return drm_vblank_get(crtc->dev, drm_crtc_index(crtc));
1200 }
1201 EXPORT_SYMBOL(drm_crtc_vblank_get);
1202 
drm_vblank_put(struct drm_device * dev,unsigned int pipe)1203 void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
1204 {
1205 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1206 
1207 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1208 		return;
1209 
1210 	if (drm_WARN_ON(dev, atomic_read(&vblank->refcount) == 0))
1211 		return;
1212 
1213 	/* Last user schedules interrupt disable */
1214 	if (atomic_dec_and_test(&vblank->refcount)) {
1215 		if (drm_vblank_offdelay == 0)
1216 			return;
1217 		else if (drm_vblank_offdelay < 0)
1218 			vblank_disable_fn(&vblank->disable_timer);
1219 		else if (!dev->vblank_disable_immediate)
1220 			mod_timer(&vblank->disable_timer,
1221 				  jiffies + ((drm_vblank_offdelay * HZ)/1000));
1222 	}
1223 }
1224 
1225 /**
1226  * drm_crtc_vblank_put - give up ownership of vblank events
1227  * @crtc: which counter to give up
1228  *
1229  * Release ownership of a given vblank counter, turning off interrupts
1230  * if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
1231  */
drm_crtc_vblank_put(struct drm_crtc * crtc)1232 void drm_crtc_vblank_put(struct drm_crtc *crtc)
1233 {
1234 	drm_vblank_put(crtc->dev, drm_crtc_index(crtc));
1235 }
1236 EXPORT_SYMBOL(drm_crtc_vblank_put);
1237 
1238 /**
1239  * drm_wait_one_vblank - wait for one vblank
1240  * @dev: DRM device
1241  * @pipe: CRTC index
1242  *
1243  * This waits for one vblank to pass on @pipe, using the irq driver interfaces.
1244  * It is a failure to call this when the vblank irq for @pipe is disabled, e.g.
1245  * due to lack of driver support or because the crtc is off.
1246  *
1247  * This is the legacy version of drm_crtc_wait_one_vblank().
1248  */
drm_wait_one_vblank(struct drm_device * dev,unsigned int pipe)1249 void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe)
1250 {
1251 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1252 	int ret;
1253 	u64 last;
1254 
1255 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1256 		return;
1257 
1258 	ret = drm_vblank_get(dev, pipe);
1259 	if (drm_WARN(dev, ret, "vblank not available on crtc %i, ret=%i\n",
1260 		     pipe, ret))
1261 		return;
1262 
1263 	last = drm_vblank_count(dev, pipe);
1264 
1265 	ret = wait_event_timeout(vblank->queue,
1266 				 last != drm_vblank_count(dev, pipe),
1267 				 msecs_to_jiffies(100));
1268 
1269 	drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe);
1270 
1271 	drm_vblank_put(dev, pipe);
1272 }
1273 EXPORT_SYMBOL(drm_wait_one_vblank);
1274 
1275 /**
1276  * drm_crtc_wait_one_vblank - wait for one vblank
1277  * @crtc: DRM crtc
1278  *
1279  * This waits for one vblank to pass on @crtc, using the irq driver interfaces.
1280  * It is a failure to call this when the vblank irq for @crtc is disabled, e.g.
1281  * due to lack of driver support or because the crtc is off.
1282  */
drm_crtc_wait_one_vblank(struct drm_crtc * crtc)1283 void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
1284 {
1285 	drm_wait_one_vblank(crtc->dev, drm_crtc_index(crtc));
1286 }
1287 EXPORT_SYMBOL(drm_crtc_wait_one_vblank);
1288 
1289 /**
1290  * drm_crtc_vblank_off - disable vblank events on a CRTC
1291  * @crtc: CRTC in question
1292  *
1293  * Drivers can use this function to shut down the vblank interrupt handling when
1294  * disabling a crtc. This function ensures that the latest vblank frame count is
1295  * stored so that drm_vblank_on can restore it again.
1296  *
1297  * Drivers must use this function when the hardware vblank counter can get
1298  * reset, e.g. when suspending or disabling the @crtc in general.
1299  */
drm_crtc_vblank_off(struct drm_crtc * crtc)1300 void drm_crtc_vblank_off(struct drm_crtc *crtc)
1301 {
1302 	struct drm_device *dev = crtc->dev;
1303 	unsigned int pipe = drm_crtc_index(crtc);
1304 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1305 	struct drm_pending_vblank_event *e, *t;
1306 	ktime_t now;
1307 	u64 seq;
1308 
1309 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1310 		return;
1311 
1312 	/*
1313 	 * Grab event_lock early to prevent vblank work from being scheduled
1314 	 * while we're in the middle of shutting down vblank interrupts
1315 	 */
1316 	spin_lock_irq(&dev->event_lock);
1317 
1318 	spin_lock(&dev->vbl_lock);
1319 	drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n",
1320 		    pipe, vblank->enabled, vblank->inmodeset);
1321 
1322 	/* Avoid redundant vblank disables without previous
1323 	 * drm_crtc_vblank_on(). */
1324 	if (drm_core_check_feature(dev, DRIVER_ATOMIC) || !vblank->inmodeset)
1325 		drm_vblank_disable_and_save(dev, pipe);
1326 
1327 	wake_up(&vblank->queue);
1328 
1329 	/*
1330 	 * Prevent subsequent drm_vblank_get() from re-enabling
1331 	 * the vblank interrupt by bumping the refcount.
1332 	 */
1333 	if (!vblank->inmodeset) {
1334 		atomic_inc(&vblank->refcount);
1335 		vblank->inmodeset = 1;
1336 	}
1337 	spin_unlock(&dev->vbl_lock);
1338 
1339 	/* Send any queued vblank events, lest the natives grow disquiet */
1340 	seq = drm_vblank_count_and_time(dev, pipe, &now);
1341 
1342 	list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
1343 		if (e->pipe != pipe)
1344 			continue;
1345 		drm_dbg_core(dev, "Sending premature vblank event on disable: "
1346 			     "wanted %llu, current %llu\n",
1347 			     e->sequence, seq);
1348 		list_del(&e->base.link);
1349 		drm_vblank_put(dev, pipe);
1350 		send_vblank_event(dev, e, seq, now);
1351 	}
1352 
1353 	/* Cancel any leftover pending vblank work */
1354 	drm_vblank_cancel_pending_works(vblank);
1355 
1356 	spin_unlock_irq(&dev->event_lock);
1357 
1358 	/* Will be reset by the modeset helpers when re-enabling the crtc by
1359 	 * calling drm_calc_timestamping_constants(). */
1360 	vblank->hwmode.crtc_clock = 0;
1361 
1362 	/* Wait for any vblank work that's still executing to finish */
1363 	drm_vblank_flush_worker(vblank);
1364 }
1365 EXPORT_SYMBOL(drm_crtc_vblank_off);
1366 
1367 /**
1368  * drm_crtc_vblank_reset - reset vblank state to off on a CRTC
1369  * @crtc: CRTC in question
1370  *
1371  * Drivers can use this function to reset the vblank state to off at load time.
1372  * Drivers should use this together with the drm_crtc_vblank_off() and
1373  * drm_crtc_vblank_on() functions. The difference compared to
1374  * drm_crtc_vblank_off() is that this function doesn't save the vblank counter
1375  * and hence doesn't need to call any driver hooks.
1376  *
1377  * This is useful for recovering driver state e.g. on driver load, or on resume.
1378  */
drm_crtc_vblank_reset(struct drm_crtc * crtc)1379 void drm_crtc_vblank_reset(struct drm_crtc *crtc)
1380 {
1381 	struct drm_device *dev = crtc->dev;
1382 	unsigned int pipe = drm_crtc_index(crtc);
1383 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1384 
1385 	spin_lock_irq(&dev->vbl_lock);
1386 	/*
1387 	 * Prevent subsequent drm_vblank_get() from enabling the vblank
1388 	 * interrupt by bumping the refcount.
1389 	 */
1390 	if (!vblank->inmodeset) {
1391 		atomic_inc(&vblank->refcount);
1392 		vblank->inmodeset = 1;
1393 	}
1394 	spin_unlock_irq(&dev->vbl_lock);
1395 
1396 	drm_WARN_ON(dev, !list_empty(&dev->vblank_event_list));
1397 	drm_WARN_ON(dev, !list_empty(&vblank->pending_work));
1398 }
1399 EXPORT_SYMBOL(drm_crtc_vblank_reset);
1400 
1401 /**
1402  * drm_crtc_set_max_vblank_count - configure the hw max vblank counter value
1403  * @crtc: CRTC in question
1404  * @max_vblank_count: max hardware vblank counter value
1405  *
1406  * Update the maximum hardware vblank counter value for @crtc
1407  * at runtime. Useful for hardware where the operation of the
1408  * hardware vblank counter depends on the currently active
1409  * display configuration.
1410  *
1411  * For example, if the hardware vblank counter does not work
1412  * when a specific connector is active the maximum can be set
1413  * to zero. And when that specific connector isn't active the
1414  * maximum can again be set to the appropriate non-zero value.
1415  *
1416  * If used, must be called before drm_vblank_on().
1417  */
drm_crtc_set_max_vblank_count(struct drm_crtc * crtc,u32 max_vblank_count)1418 void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc,
1419 				   u32 max_vblank_count)
1420 {
1421 	struct drm_device *dev = crtc->dev;
1422 	unsigned int pipe = drm_crtc_index(crtc);
1423 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1424 
1425 	drm_WARN_ON(dev, dev->max_vblank_count);
1426 	drm_WARN_ON(dev, !READ_ONCE(vblank->inmodeset));
1427 
1428 	vblank->max_vblank_count = max_vblank_count;
1429 }
1430 EXPORT_SYMBOL(drm_crtc_set_max_vblank_count);
1431 
1432 /**
1433  * drm_crtc_vblank_on - enable vblank events on a CRTC
1434  * @crtc: CRTC in question
1435  *
1436  * This functions restores the vblank interrupt state captured with
1437  * drm_crtc_vblank_off() again and is generally called when enabling @crtc. Note
1438  * that calls to drm_crtc_vblank_on() and drm_crtc_vblank_off() can be
1439  * unbalanced and so can also be unconditionally called in driver load code to
1440  * reflect the current hardware state of the crtc.
1441  */
drm_crtc_vblank_on(struct drm_crtc * crtc)1442 void drm_crtc_vblank_on(struct drm_crtc *crtc)
1443 {
1444 	struct drm_device *dev = crtc->dev;
1445 	unsigned int pipe = drm_crtc_index(crtc);
1446 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1447 
1448 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1449 		return;
1450 
1451 	spin_lock_irq(&dev->vbl_lock);
1452 	drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n",
1453 		    pipe, vblank->enabled, vblank->inmodeset);
1454 
1455 	/* Drop our private "prevent drm_vblank_get" refcount */
1456 	if (vblank->inmodeset) {
1457 		atomic_dec(&vblank->refcount);
1458 		vblank->inmodeset = 0;
1459 	}
1460 
1461 	drm_reset_vblank_timestamp(dev, pipe);
1462 
1463 	/*
1464 	 * re-enable interrupts if there are users left, or the
1465 	 * user wishes vblank interrupts to be enabled all the time.
1466 	 */
1467 	if (atomic_read(&vblank->refcount) != 0 || drm_vblank_offdelay == 0)
1468 		drm_WARN_ON(dev, drm_vblank_enable(dev, pipe));
1469 	spin_unlock_irq(&dev->vbl_lock);
1470 }
1471 EXPORT_SYMBOL(drm_crtc_vblank_on);
1472 
drm_vblank_restore(struct drm_device * dev,unsigned int pipe)1473 static void drm_vblank_restore(struct drm_device *dev, unsigned int pipe)
1474 {
1475 	ktime_t t_vblank;
1476 	struct drm_vblank_crtc *vblank;
1477 	int framedur_ns;
1478 	u64 diff_ns;
1479 	u32 cur_vblank, diff = 1;
1480 	int count = DRM_TIMESTAMP_MAXRETRIES;
1481 	u32 max_vblank_count = drm_max_vblank_count(dev, pipe);
1482 
1483 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1484 		return;
1485 
1486 	assert_spin_locked(&dev->vbl_lock);
1487 	assert_spin_locked(&dev->vblank_time_lock);
1488 
1489 	vblank = &dev->vblank[pipe];
1490 	drm_WARN_ONCE(dev,
1491 		      drm_debug_enabled(DRM_UT_VBL) && !vblank->framedur_ns,
1492 		      "Cannot compute missed vblanks without frame duration\n");
1493 	framedur_ns = vblank->framedur_ns;
1494 
1495 	do {
1496 		cur_vblank = __get_vblank_counter(dev, pipe);
1497 		drm_get_last_vbltimestamp(dev, pipe, &t_vblank, false);
1498 	} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
1499 
1500 	diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time));
1501 	if (framedur_ns)
1502 		diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
1503 
1504 
1505 	drm_dbg_vbl(dev,
1506 		    "missed %d vblanks in %lld ns, frame duration=%d ns, hw_diff=%d\n",
1507 		    diff, diff_ns, framedur_ns, cur_vblank - vblank->last);
1508 	vblank->last = (cur_vblank - diff) & max_vblank_count;
1509 }
1510 
1511 /**
1512  * drm_crtc_vblank_restore - estimate missed vblanks and update vblank count.
1513  * @crtc: CRTC in question
1514  *
1515  * Power manamement features can cause frame counter resets between vblank
1516  * disable and enable. Drivers can use this function in their
1517  * &drm_crtc_funcs.enable_vblank implementation to estimate missed vblanks since
1518  * the last &drm_crtc_funcs.disable_vblank using timestamps and update the
1519  * vblank counter.
1520  *
1521  * Note that drivers must have race-free high-precision timestamping support,
1522  * i.e.  &drm_crtc_funcs.get_vblank_timestamp must be hooked up and
1523  * &drm_driver.vblank_disable_immediate must be set to indicate the
1524  * time-stamping functions are race-free against vblank hardware counter
1525  * increments.
1526  */
drm_crtc_vblank_restore(struct drm_crtc * crtc)1527 void drm_crtc_vblank_restore(struct drm_crtc *crtc)
1528 {
1529 	WARN_ON_ONCE(!crtc->funcs->get_vblank_timestamp);
1530 	WARN_ON_ONCE(!crtc->dev->vblank_disable_immediate);
1531 
1532 	drm_vblank_restore(crtc->dev, drm_crtc_index(crtc));
1533 }
1534 EXPORT_SYMBOL(drm_crtc_vblank_restore);
1535 
drm_legacy_vblank_pre_modeset(struct drm_device * dev,unsigned int pipe)1536 static void drm_legacy_vblank_pre_modeset(struct drm_device *dev,
1537 					  unsigned int pipe)
1538 {
1539 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1540 
1541 	/* vblank is not initialized (IRQ not installed ?), or has been freed */
1542 	if (!drm_dev_has_vblank(dev))
1543 		return;
1544 
1545 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1546 		return;
1547 
1548 	/*
1549 	 * To avoid all the problems that might happen if interrupts
1550 	 * were enabled/disabled around or between these calls, we just
1551 	 * have the kernel take a reference on the CRTC (just once though
1552 	 * to avoid corrupting the count if multiple, mismatch calls occur),
1553 	 * so that interrupts remain enabled in the interim.
1554 	 */
1555 	if (!vblank->inmodeset) {
1556 		vblank->inmodeset = 0x1;
1557 		if (drm_vblank_get(dev, pipe) == 0)
1558 			vblank->inmodeset |= 0x2;
1559 	}
1560 }
1561 
drm_legacy_vblank_post_modeset(struct drm_device * dev,unsigned int pipe)1562 static void drm_legacy_vblank_post_modeset(struct drm_device *dev,
1563 					   unsigned int pipe)
1564 {
1565 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1566 
1567 	/* vblank is not initialized (IRQ not installed ?), or has been freed */
1568 	if (!drm_dev_has_vblank(dev))
1569 		return;
1570 
1571 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1572 		return;
1573 
1574 	if (vblank->inmodeset) {
1575 		spin_lock_irq(&dev->vbl_lock);
1576 		drm_reset_vblank_timestamp(dev, pipe);
1577 		spin_unlock_irq(&dev->vbl_lock);
1578 
1579 		if (vblank->inmodeset & 0x2)
1580 			drm_vblank_put(dev, pipe);
1581 
1582 		vblank->inmodeset = 0;
1583 	}
1584 }
1585 
drm_legacy_modeset_ctl_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)1586 int drm_legacy_modeset_ctl_ioctl(struct drm_device *dev, void *data,
1587 				 struct drm_file *file_priv)
1588 {
1589 	struct drm_modeset_ctl *modeset = data;
1590 	unsigned int pipe;
1591 
1592 	/* If drm_vblank_init() hasn't been called yet, just no-op */
1593 	if (!drm_dev_has_vblank(dev))
1594 		return 0;
1595 
1596 	/* KMS drivers handle this internally */
1597 	if (!drm_core_check_feature(dev, DRIVER_LEGACY))
1598 		return 0;
1599 
1600 	pipe = modeset->crtc;
1601 	if (pipe >= dev->num_crtcs)
1602 		return -EINVAL;
1603 
1604 	switch (modeset->cmd) {
1605 	case _DRM_PRE_MODESET:
1606 		drm_legacy_vblank_pre_modeset(dev, pipe);
1607 		break;
1608 	case _DRM_POST_MODESET:
1609 		drm_legacy_vblank_post_modeset(dev, pipe);
1610 		break;
1611 	default:
1612 		return -EINVAL;
1613 	}
1614 
1615 	return 0;
1616 }
1617 
drm_queue_vblank_event(struct drm_device * dev,unsigned int pipe,u64 req_seq,union drm_wait_vblank * vblwait,struct drm_file * file_priv)1618 static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
1619 				  u64 req_seq,
1620 				  union drm_wait_vblank *vblwait,
1621 				  struct drm_file *file_priv)
1622 {
1623 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1624 	struct drm_pending_vblank_event *e;
1625 	ktime_t now;
1626 	u64 seq;
1627 	int ret;
1628 
1629 	e = kzalloc(sizeof(*e), GFP_KERNEL);
1630 	if (e == NULL) {
1631 		ret = -ENOMEM;
1632 		goto err_put;
1633 	}
1634 
1635 	e->pipe = pipe;
1636 	e->event.base.type = DRM_EVENT_VBLANK;
1637 	e->event.base.length = sizeof(e->event.vbl);
1638 	e->event.vbl.user_data = vblwait->request.signal;
1639 	e->event.vbl.crtc_id = 0;
1640 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
1641 		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
1642 
1643 		if (crtc)
1644 			e->event.vbl.crtc_id = crtc->base.id;
1645 	}
1646 
1647 	spin_lock_irq(&dev->event_lock);
1648 
1649 	/*
1650 	 * drm_crtc_vblank_off() might have been called after we called
1651 	 * drm_vblank_get(). drm_crtc_vblank_off() holds event_lock around the
1652 	 * vblank disable, so no need for further locking.  The reference from
1653 	 * drm_vblank_get() protects against vblank disable from another source.
1654 	 */
1655 	if (!READ_ONCE(vblank->enabled)) {
1656 		ret = -EINVAL;
1657 		goto err_unlock;
1658 	}
1659 
1660 	ret = drm_event_reserve_init_locked(dev, file_priv, &e->base,
1661 					    &e->event.base);
1662 
1663 	if (ret)
1664 		goto err_unlock;
1665 
1666 	seq = drm_vblank_count_and_time(dev, pipe, &now);
1667 
1668 	drm_dbg_core(dev, "event on vblank count %llu, current %llu, crtc %u\n",
1669 		     req_seq, seq, pipe);
1670 
1671 	trace_drm_vblank_event_queued(file_priv, pipe, req_seq);
1672 
1673 	e->sequence = req_seq;
1674 	if (drm_vblank_passed(seq, req_seq)) {
1675 		drm_vblank_put(dev, pipe);
1676 		send_vblank_event(dev, e, seq, now);
1677 		vblwait->reply.sequence = seq;
1678 	} else {
1679 		/* drm_handle_vblank_events will call drm_vblank_put */
1680 		list_add_tail(&e->base.link, &dev->vblank_event_list);
1681 		vblwait->reply.sequence = req_seq;
1682 	}
1683 
1684 	spin_unlock_irq(&dev->event_lock);
1685 
1686 	return 0;
1687 
1688 err_unlock:
1689 	spin_unlock_irq(&dev->event_lock);
1690 	kfree(e);
1691 err_put:
1692 	drm_vblank_put(dev, pipe);
1693 	return ret;
1694 }
1695 
drm_wait_vblank_is_query(union drm_wait_vblank * vblwait)1696 static bool drm_wait_vblank_is_query(union drm_wait_vblank *vblwait)
1697 {
1698 	if (vblwait->request.sequence)
1699 		return false;
1700 
1701 	return _DRM_VBLANK_RELATIVE ==
1702 		(vblwait->request.type & (_DRM_VBLANK_TYPES_MASK |
1703 					  _DRM_VBLANK_EVENT |
1704 					  _DRM_VBLANK_NEXTONMISS));
1705 }
1706 
1707 /*
1708  * Widen a 32-bit param to 64-bits.
1709  *
1710  * \param narrow 32-bit value (missing upper 32 bits)
1711  * \param near 64-bit value that should be 'close' to near
1712  *
1713  * This function returns a 64-bit value using the lower 32-bits from
1714  * 'narrow' and constructing the upper 32-bits so that the result is
1715  * as close as possible to 'near'.
1716  */
1717 
widen_32_to_64(u32 narrow,u64 near)1718 static u64 widen_32_to_64(u32 narrow, u64 near)
1719 {
1720 	return near + (s32) (narrow - near);
1721 }
1722 
drm_wait_vblank_reply(struct drm_device * dev,unsigned int pipe,struct drm_wait_vblank_reply * reply)1723 static void drm_wait_vblank_reply(struct drm_device *dev, unsigned int pipe,
1724 				  struct drm_wait_vblank_reply *reply)
1725 {
1726 	ktime_t now;
1727 	struct timespec64 ts;
1728 
1729 	/*
1730 	 * drm_wait_vblank_reply is a UAPI structure that uses 'long'
1731 	 * to store the seconds. This is safe as we always use monotonic
1732 	 * timestamps since linux-4.15.
1733 	 */
1734 	reply->sequence = drm_vblank_count_and_time(dev, pipe, &now);
1735 	ts = ktime_to_timespec64(now);
1736 	reply->tval_sec = (u32)ts.tv_sec;
1737 	reply->tval_usec = ts.tv_nsec / 1000;
1738 }
1739 
drm_wait_vblank_supported(struct drm_device * dev)1740 static bool drm_wait_vblank_supported(struct drm_device *dev)
1741 {
1742 #if IS_ENABLED(CONFIG_DRM_LEGACY)
1743 	if (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY)))
1744 		return dev->irq_enabled;
1745 #endif
1746 	return drm_dev_has_vblank(dev);
1747 }
1748 
drm_wait_vblank_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)1749 int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
1750 			  struct drm_file *file_priv)
1751 {
1752 	struct drm_crtc *crtc;
1753 	struct drm_vblank_crtc *vblank;
1754 	union drm_wait_vblank *vblwait = data;
1755 	int ret;
1756 	u64 req_seq, seq;
1757 	unsigned int pipe_index;
1758 	unsigned int flags, pipe, high_pipe;
1759 
1760 	if (!drm_wait_vblank_supported(dev))
1761 		return -EOPNOTSUPP;
1762 
1763 	if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
1764 		return -EINVAL;
1765 
1766 	if (vblwait->request.type &
1767 	    ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
1768 	      _DRM_VBLANK_HIGH_CRTC_MASK)) {
1769 		drm_dbg_core(dev,
1770 			     "Unsupported type value 0x%x, supported mask 0x%x\n",
1771 			     vblwait->request.type,
1772 			     (_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
1773 			      _DRM_VBLANK_HIGH_CRTC_MASK));
1774 		return -EINVAL;
1775 	}
1776 
1777 	flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
1778 	high_pipe = (vblwait->request.type & _DRM_VBLANK_HIGH_CRTC_MASK);
1779 	if (high_pipe)
1780 		pipe_index = high_pipe >> _DRM_VBLANK_HIGH_CRTC_SHIFT;
1781 	else
1782 		pipe_index = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
1783 
1784 	/* Convert lease-relative crtc index into global crtc index */
1785 	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
1786 		pipe = 0;
1787 		drm_for_each_crtc(crtc, dev) {
1788 			if (drm_lease_held(file_priv, crtc->base.id)) {
1789 				if (pipe_index == 0)
1790 					break;
1791 				pipe_index--;
1792 			}
1793 			pipe++;
1794 		}
1795 	} else {
1796 		pipe = pipe_index;
1797 	}
1798 
1799 	if (pipe >= dev->num_crtcs)
1800 		return -EINVAL;
1801 
1802 	vblank = &dev->vblank[pipe];
1803 
1804 	/* If the counter is currently enabled and accurate, short-circuit
1805 	 * queries to return the cached timestamp of the last vblank.
1806 	 */
1807 	if (dev->vblank_disable_immediate &&
1808 	    drm_wait_vblank_is_query(vblwait) &&
1809 	    READ_ONCE(vblank->enabled)) {
1810 		drm_wait_vblank_reply(dev, pipe, &vblwait->reply);
1811 		return 0;
1812 	}
1813 
1814 	ret = drm_vblank_get(dev, pipe);
1815 	if (ret) {
1816 		drm_dbg_core(dev,
1817 			     "crtc %d failed to acquire vblank counter, %d\n",
1818 			     pipe, ret);
1819 		return ret;
1820 	}
1821 	seq = drm_vblank_count(dev, pipe);
1822 
1823 	switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
1824 	case _DRM_VBLANK_RELATIVE:
1825 		req_seq = seq + vblwait->request.sequence;
1826 		vblwait->request.sequence = req_seq;
1827 		vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
1828 		break;
1829 	case _DRM_VBLANK_ABSOLUTE:
1830 		req_seq = widen_32_to_64(vblwait->request.sequence, seq);
1831 		break;
1832 	default:
1833 		ret = -EINVAL;
1834 		goto done;
1835 	}
1836 
1837 	if ((flags & _DRM_VBLANK_NEXTONMISS) &&
1838 	    drm_vblank_passed(seq, req_seq)) {
1839 		req_seq = seq + 1;
1840 		vblwait->request.type &= ~_DRM_VBLANK_NEXTONMISS;
1841 		vblwait->request.sequence = req_seq;
1842 	}
1843 
1844 	if (flags & _DRM_VBLANK_EVENT) {
1845 		/* must hold on to the vblank ref until the event fires
1846 		 * drm_vblank_put will be called asynchronously
1847 		 */
1848 		return drm_queue_vblank_event(dev, pipe, req_seq, vblwait, file_priv);
1849 	}
1850 
1851 	if (req_seq != seq) {
1852 		int wait;
1853 
1854 		drm_dbg_core(dev, "waiting on vblank count %llu, crtc %u\n",
1855 			     req_seq, pipe);
1856 		wait = wait_event_interruptible_timeout(vblank->queue,
1857 			drm_vblank_passed(drm_vblank_count(dev, pipe), req_seq) ||
1858 				      !READ_ONCE(vblank->enabled),
1859 			msecs_to_jiffies(3000));
1860 
1861 		switch (wait) {
1862 		case 0:
1863 			/* timeout */
1864 			ret = -EBUSY;
1865 			break;
1866 		case -ERESTARTSYS:
1867 			/* interrupted by signal */
1868 			ret = -EINTR;
1869 			break;
1870 		default:
1871 			ret = 0;
1872 			break;
1873 		}
1874 	}
1875 
1876 	if (ret != -EINTR) {
1877 		drm_wait_vblank_reply(dev, pipe, &vblwait->reply);
1878 
1879 		drm_dbg_core(dev, "crtc %d returning %u to client\n",
1880 			     pipe, vblwait->reply.sequence);
1881 	} else {
1882 		drm_dbg_core(dev, "crtc %d vblank wait interrupted by signal\n",
1883 			     pipe);
1884 	}
1885 
1886 done:
1887 	drm_vblank_put(dev, pipe);
1888 	return ret;
1889 }
1890 
drm_handle_vblank_events(struct drm_device * dev,unsigned int pipe)1891 static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
1892 {
1893 	struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
1894 	bool high_prec = false;
1895 	struct drm_pending_vblank_event *e, *t;
1896 	ktime_t now;
1897 	u64 seq;
1898 
1899 	assert_spin_locked(&dev->event_lock);
1900 
1901 	seq = drm_vblank_count_and_time(dev, pipe, &now);
1902 
1903 	list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
1904 		if (e->pipe != pipe)
1905 			continue;
1906 		if (!drm_vblank_passed(seq, e->sequence))
1907 			continue;
1908 
1909 		drm_dbg_core(dev, "vblank event on %llu, current %llu\n",
1910 			     e->sequence, seq);
1911 
1912 		list_del(&e->base.link);
1913 		drm_vblank_put(dev, pipe);
1914 		send_vblank_event(dev, e, seq, now);
1915 	}
1916 
1917 	if (crtc && crtc->funcs->get_vblank_timestamp)
1918 		high_prec = true;
1919 
1920 	trace_drm_vblank_event(pipe, seq, now, high_prec);
1921 }
1922 
1923 /**
1924  * drm_handle_vblank - handle a vblank event
1925  * @dev: DRM device
1926  * @pipe: index of CRTC where this event occurred
1927  *
1928  * Drivers should call this routine in their vblank interrupt handlers to
1929  * update the vblank counter and send any signals that may be pending.
1930  *
1931  * This is the legacy version of drm_crtc_handle_vblank().
1932  */
drm_handle_vblank(struct drm_device * dev,unsigned int pipe)1933 bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
1934 {
1935 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
1936 	unsigned long irqflags;
1937 	bool disable_irq;
1938 
1939 	if (drm_WARN_ON_ONCE(dev, !drm_dev_has_vblank(dev)))
1940 		return false;
1941 
1942 	if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
1943 		return false;
1944 
1945 	spin_lock_irqsave(&dev->event_lock, irqflags);
1946 
1947 	/* Need timestamp lock to prevent concurrent execution with
1948 	 * vblank enable/disable, as this would cause inconsistent
1949 	 * or corrupted timestamps and vblank counts.
1950 	 */
1951 	spin_lock(&dev->vblank_time_lock);
1952 
1953 	/* Vblank irq handling disabled. Nothing to do. */
1954 	if (!vblank->enabled) {
1955 		spin_unlock(&dev->vblank_time_lock);
1956 		spin_unlock_irqrestore(&dev->event_lock, irqflags);
1957 		return false;
1958 	}
1959 
1960 	drm_update_vblank_count(dev, pipe, true);
1961 
1962 	spin_unlock(&dev->vblank_time_lock);
1963 
1964 	wake_up(&vblank->queue);
1965 
1966 	/* With instant-off, we defer disabling the interrupt until after
1967 	 * we finish processing the following vblank after all events have
1968 	 * been signaled. The disable has to be last (after
1969 	 * drm_handle_vblank_events) so that the timestamp is always accurate.
1970 	 */
1971 	disable_irq = (dev->vblank_disable_immediate &&
1972 		       drm_vblank_offdelay > 0 &&
1973 		       !atomic_read(&vblank->refcount));
1974 
1975 	drm_handle_vblank_events(dev, pipe);
1976 	drm_handle_vblank_works(vblank);
1977 
1978 	spin_unlock_irqrestore(&dev->event_lock, irqflags);
1979 
1980 	if (disable_irq)
1981 		vblank_disable_fn(&vblank->disable_timer);
1982 
1983 	return true;
1984 }
1985 EXPORT_SYMBOL(drm_handle_vblank);
1986 
1987 /**
1988  * drm_crtc_handle_vblank - handle a vblank event
1989  * @crtc: where this event occurred
1990  *
1991  * Drivers should call this routine in their vblank interrupt handlers to
1992  * update the vblank counter and send any signals that may be pending.
1993  *
1994  * This is the native KMS version of drm_handle_vblank().
1995  *
1996  * Note that for a given vblank counter value drm_crtc_handle_vblank()
1997  * and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
1998  * provide a barrier: Any writes done before calling
1999  * drm_crtc_handle_vblank() will be visible to callers of the later
2000  * functions, if the vblank count is the same or a later one.
2001  *
2002  * See also &drm_vblank_crtc.count.
2003  *
2004  * Returns:
2005  * True if the event was successfully handled, false on failure.
2006  */
drm_crtc_handle_vblank(struct drm_crtc * crtc)2007 bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
2008 {
2009 	return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
2010 }
2011 EXPORT_SYMBOL(drm_crtc_handle_vblank);
2012 
2013 /*
2014  * Get crtc VBLANK count.
2015  *
2016  * \param dev DRM device
2017  * \param data user argument, pointing to a drm_crtc_get_sequence structure.
2018  * \param file_priv drm file private for the user's open file descriptor
2019  */
2020 
drm_crtc_get_sequence_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)2021 int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data,
2022 				struct drm_file *file_priv)
2023 {
2024 	struct drm_crtc *crtc;
2025 	struct drm_vblank_crtc *vblank;
2026 	int pipe;
2027 	struct drm_crtc_get_sequence *get_seq = data;
2028 	ktime_t now;
2029 	bool vblank_enabled;
2030 	int ret;
2031 
2032 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
2033 		return -EOPNOTSUPP;
2034 
2035 	if (!drm_dev_has_vblank(dev))
2036 		return -EOPNOTSUPP;
2037 
2038 	crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id);
2039 	if (!crtc)
2040 		return -ENOENT;
2041 
2042 	pipe = drm_crtc_index(crtc);
2043 
2044 	vblank = &dev->vblank[pipe];
2045 	vblank_enabled = dev->vblank_disable_immediate && READ_ONCE(vblank->enabled);
2046 
2047 	if (!vblank_enabled) {
2048 		ret = drm_crtc_vblank_get(crtc);
2049 		if (ret) {
2050 			drm_dbg_core(dev,
2051 				     "crtc %d failed to acquire vblank counter, %d\n",
2052 				     pipe, ret);
2053 			return ret;
2054 		}
2055 	}
2056 	drm_modeset_lock(&crtc->mutex, NULL);
2057 	if (crtc->state)
2058 		get_seq->active = crtc->state->enable;
2059 	else
2060 		get_seq->active = crtc->enabled;
2061 	drm_modeset_unlock(&crtc->mutex);
2062 	get_seq->sequence = drm_vblank_count_and_time(dev, pipe, &now);
2063 	get_seq->sequence_ns = ktime_to_ns(now);
2064 	if (!vblank_enabled)
2065 		drm_crtc_vblank_put(crtc);
2066 	return 0;
2067 }
2068 
2069 /*
2070  * Queue a event for VBLANK sequence
2071  *
2072  * \param dev DRM device
2073  * \param data user argument, pointing to a drm_crtc_queue_sequence structure.
2074  * \param file_priv drm file private for the user's open file descriptor
2075  */
2076 
drm_crtc_queue_sequence_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)2077 int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
2078 				  struct drm_file *file_priv)
2079 {
2080 	struct drm_crtc *crtc;
2081 	struct drm_vblank_crtc *vblank;
2082 	int pipe;
2083 	struct drm_crtc_queue_sequence *queue_seq = data;
2084 	ktime_t now;
2085 	struct drm_pending_vblank_event *e;
2086 	u32 flags;
2087 	u64 seq;
2088 	u64 req_seq;
2089 	int ret;
2090 
2091 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
2092 		return -EOPNOTSUPP;
2093 
2094 	if (!drm_dev_has_vblank(dev))
2095 		return -EOPNOTSUPP;
2096 
2097 	crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id);
2098 	if (!crtc)
2099 		return -ENOENT;
2100 
2101 	flags = queue_seq->flags;
2102 	/* Check valid flag bits */
2103 	if (flags & ~(DRM_CRTC_SEQUENCE_RELATIVE|
2104 		      DRM_CRTC_SEQUENCE_NEXT_ON_MISS))
2105 		return -EINVAL;
2106 
2107 	pipe = drm_crtc_index(crtc);
2108 
2109 	vblank = &dev->vblank[pipe];
2110 
2111 	e = kzalloc(sizeof(*e), GFP_KERNEL);
2112 	if (e == NULL)
2113 		return -ENOMEM;
2114 
2115 	ret = drm_crtc_vblank_get(crtc);
2116 	if (ret) {
2117 		drm_dbg_core(dev,
2118 			     "crtc %d failed to acquire vblank counter, %d\n",
2119 			     pipe, ret);
2120 		goto err_free;
2121 	}
2122 
2123 	seq = drm_vblank_count_and_time(dev, pipe, &now);
2124 	req_seq = queue_seq->sequence;
2125 
2126 	if (flags & DRM_CRTC_SEQUENCE_RELATIVE)
2127 		req_seq += seq;
2128 
2129 	if ((flags & DRM_CRTC_SEQUENCE_NEXT_ON_MISS) && drm_vblank_passed(seq, req_seq))
2130 		req_seq = seq + 1;
2131 
2132 	e->pipe = pipe;
2133 	e->event.base.type = DRM_EVENT_CRTC_SEQUENCE;
2134 	e->event.base.length = sizeof(e->event.seq);
2135 	e->event.seq.user_data = queue_seq->user_data;
2136 
2137 	spin_lock_irq(&dev->event_lock);
2138 
2139 	/*
2140 	 * drm_crtc_vblank_off() might have been called after we called
2141 	 * drm_crtc_vblank_get(). drm_crtc_vblank_off() holds event_lock around the
2142 	 * vblank disable, so no need for further locking.  The reference from
2143 	 * drm_crtc_vblank_get() protects against vblank disable from another source.
2144 	 */
2145 	if (!READ_ONCE(vblank->enabled)) {
2146 		ret = -EINVAL;
2147 		goto err_unlock;
2148 	}
2149 
2150 	ret = drm_event_reserve_init_locked(dev, file_priv, &e->base,
2151 					    &e->event.base);
2152 
2153 	if (ret)
2154 		goto err_unlock;
2155 
2156 	e->sequence = req_seq;
2157 
2158 	if (drm_vblank_passed(seq, req_seq)) {
2159 		drm_crtc_vblank_put(crtc);
2160 		send_vblank_event(dev, e, seq, now);
2161 		queue_seq->sequence = seq;
2162 	} else {
2163 		/* drm_handle_vblank_events will call drm_vblank_put */
2164 		list_add_tail(&e->base.link, &dev->vblank_event_list);
2165 		queue_seq->sequence = req_seq;
2166 	}
2167 
2168 	spin_unlock_irq(&dev->event_lock);
2169 	return 0;
2170 
2171 err_unlock:
2172 	spin_unlock_irq(&dev->event_lock);
2173 	drm_crtc_vblank_put(crtc);
2174 err_free:
2175 	kfree(e);
2176 	return ret;
2177 }
2178 
2179