1 /*
2 * Copyright © 2008 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 DEALINGS
21 * IN THE SOFTWARE.
22 *
23 * Authors:
24 * Eric Anholt <eric@anholt.net>
25 *
26 */
27
28 #include "linux/string.h"
29 #include "linux/bitops.h"
30 #include "drmP.h"
31 #include "drm.h"
32 #include "i915_drm.h"
33 #include "i915_drv.h"
34
35 /** @file i915_gem_tiling.c
36 *
37 * Support for managing tiling state of buffer objects.
38 *
39 * The idea behind tiling is to increase cache hit rates by rearranging
40 * pixel data so that a group of pixel accesses are in the same cacheline.
41 * Performance improvement from doing this on the back/depth buffer are on
42 * the order of 30%.
43 *
44 * Intel architectures make this somewhat more complicated, though, by
45 * adjustments made to addressing of data when the memory is in interleaved
46 * mode (matched pairs of DIMMS) to improve memory bandwidth.
47 * For interleaved memory, the CPU sends every sequential 64 bytes
48 * to an alternate memory channel so it can get the bandwidth from both.
49 *
50 * The GPU also rearranges its accesses for increased bandwidth to interleaved
51 * memory, and it matches what the CPU does for non-tiled. However, when tiled
52 * it does it a little differently, since one walks addresses not just in the
53 * X direction but also Y. So, along with alternating channels when bit
54 * 6 of the address flips, it also alternates when other bits flip -- Bits 9
55 * (every 512 bytes, an X tile scanline) and 10 (every two X tile scanlines)
56 * are common to both the 915 and 965-class hardware.
57 *
58 * The CPU also sometimes XORs in higher bits as well, to improve
59 * bandwidth doing strided access like we do so frequently in graphics. This
60 * is called "Channel XOR Randomization" in the MCH documentation. The result
61 * is that the CPU is XORing in either bit 11 or bit 17 to bit 6 of its address
62 * decode.
63 *
64 * All of this bit 6 XORing has an effect on our memory management,
65 * as we need to make sure that the 3d driver can correctly address object
66 * contents.
67 *
68 * If we don't have interleaved memory, all tiling is safe and no swizzling is
69 * required.
70 *
71 * When bit 17 is XORed in, we simply refuse to tile at all. Bit
72 * 17 is not just a page offset, so as we page an objet out and back in,
73 * individual pages in it will have different bit 17 addresses, resulting in
74 * each 64 bytes being swapped with its neighbor!
75 *
76 * Otherwise, if interleaved, we have to tell the 3d driver what the address
77 * swizzling it needs to do is, since it's writing with the CPU to the pages
78 * (bit 6 and potentially bit 11 XORed in), and the GPU is reading from the
79 * pages (bit 6, 9, and 10 XORed in), resulting in a cumulative bit swizzling
80 * required by the CPU of XORing in bit 6, 9, 10, and potentially 11, in order
81 * to match what the GPU expects.
82 */
83
84 /**
85 * Detects bit 6 swizzling of address lookup between IGD access and CPU
86 * access through main memory.
87 */
88 void
i915_gem_detect_bit_6_swizzle(struct drm_device * dev)89 i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
90 {
91 drm_i915_private_t *dev_priv = dev->dev_private;
92 uint32_t swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
93 uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
94
95 if (IS_GEN5(dev) || IS_GEN6(dev)) {
96 /* On Ironlake whatever DRAM config, GPU always do
97 * same swizzling setup.
98 */
99 swizzle_x = I915_BIT_6_SWIZZLE_9_10;
100 swizzle_y = I915_BIT_6_SWIZZLE_9;
101 } else if (IS_GEN2(dev)) {
102 /* As far as we know, the 865 doesn't have these bit 6
103 * swizzling issues.
104 */
105 swizzle_x = I915_BIT_6_SWIZZLE_NONE;
106 swizzle_y = I915_BIT_6_SWIZZLE_NONE;
107 } else if (IS_MOBILE(dev)) {
108 uint32_t dcc;
109
110 /* On mobile 9xx chipsets, channel interleave by the CPU is
111 * determined by DCC. For single-channel, neither the CPU
112 * nor the GPU do swizzling. For dual channel interleaved,
113 * the GPU's interleave is bit 9 and 10 for X tiled, and bit
114 * 9 for Y tiled. The CPU's interleave is independent, and
115 * can be based on either bit 11 (haven't seen this yet) or
116 * bit 17 (common).
117 */
118 dcc = I915_READ(DCC);
119 switch (dcc & DCC_ADDRESSING_MODE_MASK) {
120 case DCC_ADDRESSING_MODE_SINGLE_CHANNEL:
121 case DCC_ADDRESSING_MODE_DUAL_CHANNEL_ASYMMETRIC:
122 swizzle_x = I915_BIT_6_SWIZZLE_NONE;
123 swizzle_y = I915_BIT_6_SWIZZLE_NONE;
124 break;
125 case DCC_ADDRESSING_MODE_DUAL_CHANNEL_INTERLEAVED:
126 if (dcc & DCC_CHANNEL_XOR_DISABLE) {
127 /* This is the base swizzling by the GPU for
128 * tiled buffers.
129 */
130 swizzle_x = I915_BIT_6_SWIZZLE_9_10;
131 swizzle_y = I915_BIT_6_SWIZZLE_9;
132 } else if ((dcc & DCC_CHANNEL_XOR_BIT_17) == 0) {
133 /* Bit 11 swizzling by the CPU in addition. */
134 swizzle_x = I915_BIT_6_SWIZZLE_9_10_11;
135 swizzle_y = I915_BIT_6_SWIZZLE_9_11;
136 } else {
137 /* Bit 17 swizzling by the CPU in addition. */
138 swizzle_x = I915_BIT_6_SWIZZLE_9_10_17;
139 swizzle_y = I915_BIT_6_SWIZZLE_9_17;
140 }
141 break;
142 }
143 if (dcc == 0xffffffff) {
144 DRM_ERROR("Couldn't read from MCHBAR. "
145 "Disabling tiling.\n");
146 swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
147 swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
148 }
149 } else {
150 /* The 965, G33, and newer, have a very flexible memory
151 * configuration. It will enable dual-channel mode
152 * (interleaving) on as much memory as it can, and the GPU
153 * will additionally sometimes enable different bit 6
154 * swizzling for tiled objects from the CPU.
155 *
156 * Here's what I found on the G965:
157 * slot fill memory size swizzling
158 * 0A 0B 1A 1B 1-ch 2-ch
159 * 512 0 0 0 512 0 O
160 * 512 0 512 0 16 1008 X
161 * 512 0 0 512 16 1008 X
162 * 0 512 0 512 16 1008 X
163 * 1024 1024 1024 0 2048 1024 O
164 *
165 * We could probably detect this based on either the DRB
166 * matching, which was the case for the swizzling required in
167 * the table above, or from the 1-ch value being less than
168 * the minimum size of a rank.
169 */
170 if (I915_READ16(C0DRB3) != I915_READ16(C1DRB3)) {
171 swizzle_x = I915_BIT_6_SWIZZLE_NONE;
172 swizzle_y = I915_BIT_6_SWIZZLE_NONE;
173 } else {
174 swizzle_x = I915_BIT_6_SWIZZLE_9_10;
175 swizzle_y = I915_BIT_6_SWIZZLE_9;
176 }
177 }
178
179 dev_priv->mm.bit_6_swizzle_x = swizzle_x;
180 dev_priv->mm.bit_6_swizzle_y = swizzle_y;
181 }
182
183 /* Check pitch constriants for all chips & tiling formats */
184 static bool
i915_tiling_ok(struct drm_device * dev,int stride,int size,int tiling_mode)185 i915_tiling_ok(struct drm_device *dev, int stride, int size, int tiling_mode)
186 {
187 int tile_width;
188
189 /* Linear is always fine */
190 if (tiling_mode == I915_TILING_NONE)
191 return true;
192
193 if (IS_GEN2(dev) ||
194 (tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev)))
195 tile_width = 128;
196 else
197 tile_width = 512;
198
199 /* check maximum stride & object size */
200 if (INTEL_INFO(dev)->gen >= 4) {
201 /* i965 stores the end address of the gtt mapping in the fence
202 * reg, so dont bother to check the size */
203 if (stride / 128 > I965_FENCE_MAX_PITCH_VAL)
204 return false;
205 } else {
206 if (stride > 8192)
207 return false;
208
209 if (IS_GEN3(dev)) {
210 if (size > I830_FENCE_MAX_SIZE_VAL << 20)
211 return false;
212 } else {
213 if (size > I830_FENCE_MAX_SIZE_VAL << 19)
214 return false;
215 }
216 }
217
218 /* 965+ just needs multiples of tile width */
219 if (INTEL_INFO(dev)->gen >= 4) {
220 if (stride & (tile_width - 1))
221 return false;
222 return true;
223 }
224
225 /* Pre-965 needs power of two tile widths */
226 if (stride < tile_width)
227 return false;
228
229 if (stride & (stride - 1))
230 return false;
231
232 return true;
233 }
234
235 /* Is the current GTT allocation valid for the change in tiling? */
236 static bool
i915_gem_object_fence_ok(struct drm_i915_gem_object * obj,int tiling_mode)237 i915_gem_object_fence_ok(struct drm_i915_gem_object *obj, int tiling_mode)
238 {
239 u32 size;
240
241 if (tiling_mode == I915_TILING_NONE)
242 return true;
243
244 if (INTEL_INFO(obj->base.dev)->gen >= 4)
245 return true;
246
247 if (INTEL_INFO(obj->base.dev)->gen == 3) {
248 if (obj->gtt_offset & ~I915_FENCE_START_MASK)
249 return false;
250 } else {
251 if (obj->gtt_offset & ~I830_FENCE_START_MASK)
252 return false;
253 }
254
255 /*
256 * Previous chips need to be aligned to the size of the smallest
257 * fence register that can contain the object.
258 */
259 if (INTEL_INFO(obj->base.dev)->gen == 3)
260 size = 1024*1024;
261 else
262 size = 512*1024;
263
264 while (size < obj->base.size)
265 size <<= 1;
266
267 if (obj->gtt_space->size != size)
268 return false;
269
270 if (obj->gtt_offset & (size - 1))
271 return false;
272
273 return true;
274 }
275
276 /**
277 * Sets the tiling mode of an object, returning the required swizzling of
278 * bit 6 of addresses in the object.
279 */
280 int
i915_gem_set_tiling(struct drm_device * dev,void * data,struct drm_file * file)281 i915_gem_set_tiling(struct drm_device *dev, void *data,
282 struct drm_file *file)
283 {
284 struct drm_i915_gem_set_tiling *args = data;
285 drm_i915_private_t *dev_priv = dev->dev_private;
286 struct drm_i915_gem_object *obj;
287 int ret = 0;
288
289 obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
290 if (&obj->base == NULL)
291 return -ENOENT;
292
293 if (!i915_tiling_ok(dev,
294 args->stride, obj->base.size, args->tiling_mode)) {
295 drm_gem_object_unreference_unlocked(&obj->base);
296 return -EINVAL;
297 }
298
299 if (obj->pin_count) {
300 drm_gem_object_unreference_unlocked(&obj->base);
301 return -EBUSY;
302 }
303
304 if (args->tiling_mode == I915_TILING_NONE) {
305 args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
306 args->stride = 0;
307 } else {
308 if (args->tiling_mode == I915_TILING_X)
309 args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
310 else
311 args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
312
313 /* Hide bit 17 swizzling from the user. This prevents old Mesa
314 * from aborting the application on sw fallbacks to bit 17,
315 * and we use the pread/pwrite bit17 paths to swizzle for it.
316 * If there was a user that was relying on the swizzle
317 * information for drm_intel_bo_map()ed reads/writes this would
318 * break it, but we don't have any of those.
319 */
320 if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
321 args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
322 if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
323 args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;
324
325 /* If we can't handle the swizzling, make it untiled. */
326 if (args->swizzle_mode == I915_BIT_6_SWIZZLE_UNKNOWN) {
327 args->tiling_mode = I915_TILING_NONE;
328 args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
329 args->stride = 0;
330 }
331 }
332
333 mutex_lock(&dev->struct_mutex);
334 if (args->tiling_mode != obj->tiling_mode ||
335 args->stride != obj->stride) {
336 /* We need to rebind the object if its current allocation
337 * no longer meets the alignment restrictions for its new
338 * tiling mode. Otherwise we can just leave it alone, but
339 * need to ensure that any fence register is cleared.
340 */
341 i915_gem_release_mmap(obj);
342
343 obj->map_and_fenceable =
344 obj->gtt_space == NULL ||
345 (obj->gtt_offset + obj->base.size <= dev_priv->mm.gtt_mappable_end &&
346 i915_gem_object_fence_ok(obj, args->tiling_mode));
347
348 /* Rebind if we need a change of alignment */
349 if (!obj->map_and_fenceable) {
350 u32 unfenced_alignment =
351 i915_gem_get_unfenced_gtt_alignment(obj);
352 if (obj->gtt_offset & (unfenced_alignment - 1))
353 ret = i915_gem_object_unbind(obj);
354 }
355
356 if (ret == 0) {
357 obj->tiling_changed = true;
358 obj->tiling_mode = args->tiling_mode;
359 obj->stride = args->stride;
360 }
361 }
362 /* we have to maintain this existing ABI... */
363 args->stride = obj->stride;
364 args->tiling_mode = obj->tiling_mode;
365 drm_gem_object_unreference(&obj->base);
366 mutex_unlock(&dev->struct_mutex);
367
368 return ret;
369 }
370
371 /**
372 * Returns the current tiling mode and required bit 6 swizzling for the object.
373 */
374 int
i915_gem_get_tiling(struct drm_device * dev,void * data,struct drm_file * file)375 i915_gem_get_tiling(struct drm_device *dev, void *data,
376 struct drm_file *file)
377 {
378 struct drm_i915_gem_get_tiling *args = data;
379 drm_i915_private_t *dev_priv = dev->dev_private;
380 struct drm_i915_gem_object *obj;
381
382 obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
383 if (&obj->base == NULL)
384 return -ENOENT;
385
386 mutex_lock(&dev->struct_mutex);
387
388 args->tiling_mode = obj->tiling_mode;
389 switch (obj->tiling_mode) {
390 case I915_TILING_X:
391 args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
392 break;
393 case I915_TILING_Y:
394 args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
395 break;
396 case I915_TILING_NONE:
397 args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
398 break;
399 default:
400 DRM_ERROR("unknown tiling mode\n");
401 }
402
403 /* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
404 if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
405 args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
406 if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
407 args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;
408
409 drm_gem_object_unreference(&obj->base);
410 mutex_unlock(&dev->struct_mutex);
411
412 return 0;
413 }
414
415 /**
416 * Swap every 64 bytes of this page around, to account for it having a new
417 * bit 17 of its physical address and therefore being interpreted differently
418 * by the GPU.
419 */
420 static void
i915_gem_swizzle_page(struct page * page)421 i915_gem_swizzle_page(struct page *page)
422 {
423 char temp[64];
424 char *vaddr;
425 int i;
426
427 vaddr = kmap(page);
428
429 for (i = 0; i < PAGE_SIZE; i += 128) {
430 memcpy(temp, &vaddr[i], 64);
431 memcpy(&vaddr[i], &vaddr[i + 64], 64);
432 memcpy(&vaddr[i + 64], temp, 64);
433 }
434
435 kunmap(page);
436 }
437
438 void
i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object * obj)439 i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj)
440 {
441 struct drm_device *dev = obj->base.dev;
442 drm_i915_private_t *dev_priv = dev->dev_private;
443 int page_count = obj->base.size >> PAGE_SHIFT;
444 int i;
445
446 if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)
447 return;
448
449 if (obj->bit_17 == NULL)
450 return;
451
452 for (i = 0; i < page_count; i++) {
453 char new_bit_17 = page_to_phys(obj->pages[i]) >> 17;
454 if ((new_bit_17 & 0x1) !=
455 (test_bit(i, obj->bit_17) != 0)) {
456 i915_gem_swizzle_page(obj->pages[i]);
457 set_page_dirty(obj->pages[i]);
458 }
459 }
460 }
461
462 void
i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object * obj)463 i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)
464 {
465 struct drm_device *dev = obj->base.dev;
466 drm_i915_private_t *dev_priv = dev->dev_private;
467 int page_count = obj->base.size >> PAGE_SHIFT;
468 int i;
469
470 if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)
471 return;
472
473 if (obj->bit_17 == NULL) {
474 obj->bit_17 = kmalloc(BITS_TO_LONGS(page_count) *
475 sizeof(long), GFP_KERNEL);
476 if (obj->bit_17 == NULL) {
477 DRM_ERROR("Failed to allocate memory for bit 17 "
478 "record\n");
479 return;
480 }
481 }
482
483 for (i = 0; i < page_count; i++) {
484 if (page_to_phys(obj->pages[i]) & (1 << 17))
485 __set_bit(i, obj->bit_17);
486 else
487 __clear_bit(i, obj->bit_17);
488 }
489 }
490