1 /*
2 * Copyright © 2014 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 *
23 * Authors:
24 * Daniel Vetter <daniel.vetter@ffwll.ch>
25 */
26
27 /**
28 * DOC: frontbuffer tracking
29 *
30 * Many features require us to track changes to the currently active
31 * frontbuffer, especially rendering targeted at the frontbuffer.
32 *
33 * To be able to do so we track frontbuffers using a bitmask for all possible
34 * frontbuffer slots through intel_frontbuffer_track(). The functions in this
35 * file are then called when the contents of the frontbuffer are invalidated,
36 * when frontbuffer rendering has stopped again to flush out all the changes
37 * and when the frontbuffer is exchanged with a flip. Subsystems interested in
38 * frontbuffer changes (e.g. PSR, FBC, DRRS) should directly put their callbacks
39 * into the relevant places and filter for the frontbuffer slots that they are
40 * interested int.
41 *
42 * On a high level there are two types of powersaving features. The first one
43 * work like a special cache (FBC and PSR) and are interested when they should
44 * stop caching and when to restart caching. This is done by placing callbacks
45 * into the invalidate and the flush functions: At invalidate the caching must
46 * be stopped and at flush time it can be restarted. And maybe they need to know
47 * when the frontbuffer changes (e.g. when the hw doesn't initiate an invalidate
48 * and flush on its own) which can be achieved with placing callbacks into the
49 * flip functions.
50 *
51 * The other type of display power saving feature only cares about busyness
52 * (e.g. DRRS). In that case all three (invalidate, flush and flip) indicate
53 * busyness. There is no direct way to detect idleness. Instead an idle timer
54 * work delayed work should be started from the flush and flip functions and
55 * cancelled as soon as busyness is detected.
56 */
57
58 #include "i915_drv.h"
59 #include "intel_display_trace.h"
60 #include "intel_display_types.h"
61 #include "intel_dp.h"
62 #include "intel_drrs.h"
63 #include "intel_fbc.h"
64 #include "intel_frontbuffer.h"
65 #include "intel_psr.h"
66
67 /**
68 * frontbuffer_flush - flush frontbuffer
69 * @i915: i915 device
70 * @frontbuffer_bits: frontbuffer plane tracking bits
71 * @origin: which operation caused the flush
72 *
73 * This function gets called every time rendering on the given planes has
74 * completed and frontbuffer caching can be started again. Flushes will get
75 * delayed if they're blocked by some outstanding asynchronous rendering.
76 *
77 * Can be called without any locks held.
78 */
frontbuffer_flush(struct drm_i915_private * i915,unsigned int frontbuffer_bits,enum fb_op_origin origin)79 static void frontbuffer_flush(struct drm_i915_private *i915,
80 unsigned int frontbuffer_bits,
81 enum fb_op_origin origin)
82 {
83 /* Delay flushing when rings are still busy.*/
84 spin_lock(&i915->display.fb_tracking.lock);
85 frontbuffer_bits &= ~i915->display.fb_tracking.busy_bits;
86 spin_unlock(&i915->display.fb_tracking.lock);
87
88 if (!frontbuffer_bits)
89 return;
90
91 trace_intel_frontbuffer_flush(i915, frontbuffer_bits, origin);
92
93 might_sleep();
94 intel_drrs_flush(i915, frontbuffer_bits);
95 intel_psr_flush(i915, frontbuffer_bits, origin);
96 intel_fbc_flush(i915, frontbuffer_bits, origin);
97 }
98
99 /**
100 * intel_frontbuffer_flip_prepare - prepare asynchronous frontbuffer flip
101 * @i915: i915 device
102 * @frontbuffer_bits: frontbuffer plane tracking bits
103 *
104 * This function gets called after scheduling a flip on @obj. The actual
105 * frontbuffer flushing will be delayed until completion is signalled with
106 * intel_frontbuffer_flip_complete. If an invalidate happens in between this
107 * flush will be cancelled.
108 *
109 * Can be called without any locks held.
110 */
intel_frontbuffer_flip_prepare(struct drm_i915_private * i915,unsigned frontbuffer_bits)111 void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915,
112 unsigned frontbuffer_bits)
113 {
114 spin_lock(&i915->display.fb_tracking.lock);
115 i915->display.fb_tracking.flip_bits |= frontbuffer_bits;
116 /* Remove stale busy bits due to the old buffer. */
117 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
118 spin_unlock(&i915->display.fb_tracking.lock);
119 }
120
121 /**
122 * intel_frontbuffer_flip_complete - complete asynchronous frontbuffer flip
123 * @i915: i915 device
124 * @frontbuffer_bits: frontbuffer plane tracking bits
125 *
126 * This function gets called after the flip has been latched and will complete
127 * on the next vblank. It will execute the flush if it hasn't been cancelled yet.
128 *
129 * Can be called without any locks held.
130 */
intel_frontbuffer_flip_complete(struct drm_i915_private * i915,unsigned frontbuffer_bits)131 void intel_frontbuffer_flip_complete(struct drm_i915_private *i915,
132 unsigned frontbuffer_bits)
133 {
134 spin_lock(&i915->display.fb_tracking.lock);
135 /* Mask any cancelled flips. */
136 frontbuffer_bits &= i915->display.fb_tracking.flip_bits;
137 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits;
138 spin_unlock(&i915->display.fb_tracking.lock);
139
140 if (frontbuffer_bits)
141 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
142 }
143
144 /**
145 * intel_frontbuffer_flip - synchronous frontbuffer flip
146 * @i915: i915 device
147 * @frontbuffer_bits: frontbuffer plane tracking bits
148 *
149 * This function gets called after scheduling a flip on @obj. This is for
150 * synchronous plane updates which will happen on the next vblank and which will
151 * not get delayed by pending gpu rendering.
152 *
153 * Can be called without any locks held.
154 */
intel_frontbuffer_flip(struct drm_i915_private * i915,unsigned frontbuffer_bits)155 void intel_frontbuffer_flip(struct drm_i915_private *i915,
156 unsigned frontbuffer_bits)
157 {
158 spin_lock(&i915->display.fb_tracking.lock);
159 /* Remove stale busy bits due to the old buffer. */
160 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
161 spin_unlock(&i915->display.fb_tracking.lock);
162
163 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
164 }
165
__intel_fb_invalidate(struct intel_frontbuffer * front,enum fb_op_origin origin,unsigned int frontbuffer_bits)166 void __intel_fb_invalidate(struct intel_frontbuffer *front,
167 enum fb_op_origin origin,
168 unsigned int frontbuffer_bits)
169 {
170 struct drm_i915_private *i915 = intel_bo_to_i915(front->obj);
171
172 if (origin == ORIGIN_CS) {
173 spin_lock(&i915->display.fb_tracking.lock);
174 i915->display.fb_tracking.busy_bits |= frontbuffer_bits;
175 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits;
176 spin_unlock(&i915->display.fb_tracking.lock);
177 }
178
179 trace_intel_frontbuffer_invalidate(i915, frontbuffer_bits, origin);
180
181 might_sleep();
182 intel_psr_invalidate(i915, frontbuffer_bits, origin);
183 intel_drrs_invalidate(i915, frontbuffer_bits);
184 intel_fbc_invalidate(i915, frontbuffer_bits, origin);
185 }
186
__intel_fb_flush(struct intel_frontbuffer * front,enum fb_op_origin origin,unsigned int frontbuffer_bits)187 void __intel_fb_flush(struct intel_frontbuffer *front,
188 enum fb_op_origin origin,
189 unsigned int frontbuffer_bits)
190 {
191 struct drm_i915_private *i915 = intel_bo_to_i915(front->obj);
192
193 if (origin == ORIGIN_CS) {
194 spin_lock(&i915->display.fb_tracking.lock);
195 /* Filter out new bits since rendering started. */
196 frontbuffer_bits &= i915->display.fb_tracking.busy_bits;
197 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
198 spin_unlock(&i915->display.fb_tracking.lock);
199 }
200
201 if (frontbuffer_bits)
202 frontbuffer_flush(i915, frontbuffer_bits, origin);
203 }
204
frontbuffer_active(struct i915_active * ref)205 static int frontbuffer_active(struct i915_active *ref)
206 {
207 struct intel_frontbuffer *front =
208 container_of(ref, typeof(*front), write);
209
210 kref_get(&front->ref);
211 return 0;
212 }
213
frontbuffer_retire(struct i915_active * ref)214 static void frontbuffer_retire(struct i915_active *ref)
215 {
216 struct intel_frontbuffer *front =
217 container_of(ref, typeof(*front), write);
218
219 intel_frontbuffer_flush(front, ORIGIN_CS);
220 intel_frontbuffer_put(front);
221 }
222
frontbuffer_release(struct kref * ref)223 static void frontbuffer_release(struct kref *ref)
224 __releases(&intel_bo_to_i915(front->obj)->display.fb_tracking.lock)
225 {
226 struct intel_frontbuffer *front =
227 container_of(ref, typeof(*front), ref);
228 struct drm_i915_gem_object *obj = front->obj;
229
230 drm_WARN_ON(&intel_bo_to_i915(obj)->drm, atomic_read(&front->bits));
231
232 i915_ggtt_clear_scanout(obj);
233
234 i915_gem_object_set_frontbuffer(obj, NULL);
235 spin_unlock(&intel_bo_to_i915(obj)->display.fb_tracking.lock);
236
237 i915_active_fini(&front->write);
238
239 i915_gem_object_put(obj);
240 kfree_rcu(front, rcu);
241 }
242
243 struct intel_frontbuffer *
intel_frontbuffer_get(struct drm_i915_gem_object * obj)244 intel_frontbuffer_get(struct drm_i915_gem_object *obj)
245 {
246 struct drm_i915_private *i915 = intel_bo_to_i915(obj);
247 struct intel_frontbuffer *front, *cur;
248
249 front = i915_gem_object_get_frontbuffer(obj);
250 if (front)
251 return front;
252
253 front = kmalloc(sizeof(*front), GFP_KERNEL);
254 if (!front)
255 return NULL;
256
257 front->obj = obj;
258 kref_init(&front->ref);
259 atomic_set(&front->bits, 0);
260 i915_active_init(&front->write,
261 frontbuffer_active,
262 frontbuffer_retire,
263 I915_ACTIVE_RETIRE_SLEEPS);
264
265 spin_lock(&i915->display.fb_tracking.lock);
266 cur = i915_gem_object_set_frontbuffer(obj, front);
267 spin_unlock(&i915->display.fb_tracking.lock);
268 if (cur != front)
269 kfree(front);
270 return cur;
271 }
272
intel_frontbuffer_put(struct intel_frontbuffer * front)273 void intel_frontbuffer_put(struct intel_frontbuffer *front)
274 {
275 kref_put_lock(&front->ref,
276 frontbuffer_release,
277 &intel_bo_to_i915(front->obj)->display.fb_tracking.lock);
278 }
279
280 /**
281 * intel_frontbuffer_track - update frontbuffer tracking
282 * @old: current buffer for the frontbuffer slots
283 * @new: new buffer for the frontbuffer slots
284 * @frontbuffer_bits: bitmask of frontbuffer slots
285 *
286 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
287 * from @old and setting them in @new. Both @old and @new can be NULL.
288 */
intel_frontbuffer_track(struct intel_frontbuffer * old,struct intel_frontbuffer * new,unsigned int frontbuffer_bits)289 void intel_frontbuffer_track(struct intel_frontbuffer *old,
290 struct intel_frontbuffer *new,
291 unsigned int frontbuffer_bits)
292 {
293 /*
294 * Control of individual bits within the mask are guarded by
295 * the owning plane->mutex, i.e. we can never see concurrent
296 * manipulation of individual bits. But since the bitfield as a whole
297 * is updated using RMW, we need to use atomics in order to update
298 * the bits.
299 */
300 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
301 BITS_PER_TYPE(atomic_t));
302 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 32);
303 BUILD_BUG_ON(I915_MAX_PLANES > INTEL_FRONTBUFFER_BITS_PER_PIPE);
304
305 if (old) {
306 drm_WARN_ON(&intel_bo_to_i915(old->obj)->drm,
307 !(atomic_read(&old->bits) & frontbuffer_bits));
308 atomic_andnot(frontbuffer_bits, &old->bits);
309 }
310
311 if (new) {
312 drm_WARN_ON(&intel_bo_to_i915(new->obj)->drm,
313 atomic_read(&new->bits) & frontbuffer_bits);
314 atomic_or(frontbuffer_bits, &new->bits);
315 }
316 }
317