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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 "gem/i915_gem_object_frontbuffer.h"
59#include "i915_active.h"
60#include "i915_drv.h"
61#include "intel_display_trace.h"
62#include "intel_display_types.h"
63#include "intel_dp.h"
64#include "intel_drrs.h"
65#include "intel_fbc.h"
66#include "intel_frontbuffer.h"
67#include "intel_psr.h"
68
69/**
70 * frontbuffer_flush - flush frontbuffer
71 * @i915: i915 device
72 * @frontbuffer_bits: frontbuffer plane tracking bits
73 * @origin: which operation caused the flush
74 *
75 * This function gets called every time rendering on the given planes has
76 * completed and frontbuffer caching can be started again. Flushes will get
77 * delayed if they're blocked by some outstanding asynchronous rendering.
78 *
79 * Can be called without any locks held.
80 */
81static void frontbuffer_flush(struct drm_i915_private *i915,
82 unsigned int frontbuffer_bits,
83 enum fb_op_origin origin)
84{
85 /* Delay flushing when rings are still busy.*/
86 spin_lock(&i915->display.fb_tracking.lock);
87 frontbuffer_bits &= ~i915->display.fb_tracking.busy_bits;
88 spin_unlock(&i915->display.fb_tracking.lock);
89
90 if (!frontbuffer_bits)
91 return;
92
93 trace_intel_frontbuffer_flush(i915, frontbuffer_bits, origin);
94
95 might_sleep();
96 intel_drrs_flush(i915, frontbuffer_bits);
97 intel_psr_flush(i915, frontbuffer_bits, origin);
98 intel_fbc_flush(i915, frontbuffer_bits, origin);
99}
100
101/**
102 * intel_frontbuffer_flip_prepare - prepare asynchronous frontbuffer flip
103 * @i915: i915 device
104 * @frontbuffer_bits: frontbuffer plane tracking bits
105 *
106 * This function gets called after scheduling a flip on @obj. The actual
107 * frontbuffer flushing will be delayed until completion is signalled with
108 * intel_frontbuffer_flip_complete. If an invalidate happens in between this
109 * flush will be cancelled.
110 *
111 * Can be called without any locks held.
112 */
113void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915,
114 unsigned frontbuffer_bits)
115{
116 spin_lock(&i915->display.fb_tracking.lock);
117 i915->display.fb_tracking.flip_bits |= frontbuffer_bits;
118 /* Remove stale busy bits due to the old buffer. */
119 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
120 spin_unlock(&i915->display.fb_tracking.lock);
121}
122
123/**
124 * intel_frontbuffer_flip_complete - complete asynchronous frontbuffer flip
125 * @i915: i915 device
126 * @frontbuffer_bits: frontbuffer plane tracking bits
127 *
128 * This function gets called after the flip has been latched and will complete
129 * on the next vblank. It will execute the flush if it hasn't been cancelled yet.
130 *
131 * Can be called without any locks held.
132 */
133void intel_frontbuffer_flip_complete(struct drm_i915_private *i915,
134 unsigned frontbuffer_bits)
135{
136 spin_lock(&i915->display.fb_tracking.lock);
137 /* Mask any cancelled flips. */
138 frontbuffer_bits &= i915->display.fb_tracking.flip_bits;
139 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits;
140 spin_unlock(&i915->display.fb_tracking.lock);
141
142 if (frontbuffer_bits)
143 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
144}
145
146/**
147 * intel_frontbuffer_flip - synchronous frontbuffer flip
148 * @i915: i915 device
149 * @frontbuffer_bits: frontbuffer plane tracking bits
150 *
151 * This function gets called after scheduling a flip on @obj. This is for
152 * synchronous plane updates which will happen on the next vblank and which will
153 * not get delayed by pending gpu rendering.
154 *
155 * Can be called without any locks held.
156 */
157void intel_frontbuffer_flip(struct drm_i915_private *i915,
158 unsigned frontbuffer_bits)
159{
160 spin_lock(&i915->display.fb_tracking.lock);
161 /* Remove stale busy bits due to the old buffer. */
162 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
163 spin_unlock(&i915->display.fb_tracking.lock);
164
165 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
166}
167
168void __intel_fb_invalidate(struct intel_frontbuffer *front,
169 enum fb_op_origin origin,
170 unsigned int frontbuffer_bits)
171{
172 struct drm_i915_private *i915 = intel_bo_to_i915(front->obj);
173
174 if (origin == ORIGIN_CS) {
175 spin_lock(&i915->display.fb_tracking.lock);
176 i915->display.fb_tracking.busy_bits |= frontbuffer_bits;
177 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits;
178 spin_unlock(&i915->display.fb_tracking.lock);
179 }
180
181 trace_intel_frontbuffer_invalidate(i915, frontbuffer_bits, origin);
182
183 might_sleep();
184 intel_psr_invalidate(i915, frontbuffer_bits, origin);
185 intel_drrs_invalidate(i915, frontbuffer_bits);
186 intel_fbc_invalidate(i915, frontbuffer_bits, origin);
187}
188
189void __intel_fb_flush(struct intel_frontbuffer *front,
190 enum fb_op_origin origin,
191 unsigned int frontbuffer_bits)
192{
193 struct drm_i915_private *i915 = intel_bo_to_i915(front->obj);
194
195 if (origin == ORIGIN_CS) {
196 spin_lock(&i915->display.fb_tracking.lock);
197 /* Filter out new bits since rendering started. */
198 frontbuffer_bits &= i915->display.fb_tracking.busy_bits;
199 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits;
200 spin_unlock(&i915->display.fb_tracking.lock);
201 }
202
203 if (frontbuffer_bits)
204 frontbuffer_flush(i915, frontbuffer_bits, origin);
205}
206
207static void intel_frontbuffer_flush_work(struct work_struct *work)
208{
209 struct intel_frontbuffer *front =
210 container_of(work, struct intel_frontbuffer, flush_work);
211
212 i915_gem_object_flush_if_display(front->obj);
213 intel_frontbuffer_flush(front, ORIGIN_DIRTYFB);
214 intel_frontbuffer_put(front);
215}
216
217/**
218 * intel_frontbuffer_queue_flush - queue flushing frontbuffer object
219 * @front: GEM object to flush
220 *
221 * This function is targeted for our dirty callback for queueing flush when
222 * dma fence is signales
223 */
224void intel_frontbuffer_queue_flush(struct intel_frontbuffer *front)
225{
226 if (!front)
227 return;
228
229 kref_get(&front->ref);
230 if (!schedule_work(&front->flush_work))
231 intel_frontbuffer_put(front);
232}
233
234static int frontbuffer_active(struct i915_active *ref)
235{
236 struct intel_frontbuffer *front =
237 container_of(ref, typeof(*front), write);
238
239 kref_get(&front->ref);
240 return 0;
241}
242
243static void frontbuffer_retire(struct i915_active *ref)
244{
245 struct intel_frontbuffer *front =
246 container_of(ref, typeof(*front), write);
247
248 intel_frontbuffer_flush(front, ORIGIN_CS);
249 intel_frontbuffer_put(front);
250}
251
252static void frontbuffer_release(struct kref *ref)
253 __releases(&intel_bo_to_i915(front->obj)->display.fb_tracking.lock)
254{
255 struct intel_frontbuffer *ret, *front =
256 container_of(ref, typeof(*front), ref);
257 struct drm_i915_gem_object *obj = front->obj;
258
259 drm_WARN_ON(&intel_bo_to_i915(obj)->drm, atomic_read(&front->bits));
260
261 i915_ggtt_clear_scanout(obj);
262
263 ret = i915_gem_object_set_frontbuffer(obj, NULL);
264 drm_WARN_ON(&intel_bo_to_i915(obj)->drm, ret);
265 spin_unlock(&intel_bo_to_i915(obj)->display.fb_tracking.lock);
266
267 i915_active_fini(&front->write);
268 kfree_rcu(front, rcu);
269}
270
271struct intel_frontbuffer *
272intel_frontbuffer_get(struct drm_i915_gem_object *obj)
273{
274 struct drm_i915_private *i915 = intel_bo_to_i915(obj);
275 struct intel_frontbuffer *front, *cur;
276
277 front = i915_gem_object_get_frontbuffer(obj);
278 if (front)
279 return front;
280
281 front = kmalloc(sizeof(*front), GFP_KERNEL);
282 if (!front)
283 return NULL;
284
285 front->obj = obj;
286 kref_init(&front->ref);
287 atomic_set(&front->bits, 0);
288 i915_active_init(&front->write,
289 frontbuffer_active,
290 frontbuffer_retire,
291 I915_ACTIVE_RETIRE_SLEEPS);
292 INIT_WORK(&front->flush_work, intel_frontbuffer_flush_work);
293
294 spin_lock(&i915->display.fb_tracking.lock);
295 cur = i915_gem_object_set_frontbuffer(obj, front);
296 spin_unlock(&i915->display.fb_tracking.lock);
297 if (cur != front)
298 kfree(front);
299 return cur;
300}
301
302void intel_frontbuffer_put(struct intel_frontbuffer *front)
303{
304 kref_put_lock(&front->ref,
305 frontbuffer_release,
306 &intel_bo_to_i915(front->obj)->display.fb_tracking.lock);
307}
308
309/**
310 * intel_frontbuffer_track - update frontbuffer tracking
311 * @old: current buffer for the frontbuffer slots
312 * @new: new buffer for the frontbuffer slots
313 * @frontbuffer_bits: bitmask of frontbuffer slots
314 *
315 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
316 * from @old and setting them in @new. Both @old and @new can be NULL.
317 */
318void intel_frontbuffer_track(struct intel_frontbuffer *old,
319 struct intel_frontbuffer *new,
320 unsigned int frontbuffer_bits)
321{
322 /*
323 * Control of individual bits within the mask are guarded by
324 * the owning plane->mutex, i.e. we can never see concurrent
325 * manipulation of individual bits. But since the bitfield as a whole
326 * is updated using RMW, we need to use atomics in order to update
327 * the bits.
328 */
329 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
330 BITS_PER_TYPE(atomic_t));
331 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 32);
332 BUILD_BUG_ON(I915_MAX_PLANES > INTEL_FRONTBUFFER_BITS_PER_PIPE);
333
334 if (old) {
335 drm_WARN_ON(&intel_bo_to_i915(old->obj)->drm,
336 !(atomic_read(&old->bits) & frontbuffer_bits));
337 atomic_andnot(frontbuffer_bits, &old->bits);
338 }
339
340 if (new) {
341 drm_WARN_ON(&intel_bo_to_i915(new->obj)->drm,
342 atomic_read(&new->bits) & frontbuffer_bits);
343 atomic_or(frontbuffer_bits, &new->bits);
344 }
345}
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 "display/intel_dp.h"
59
60#include "i915_drv.h"
61#include "intel_display_types.h"
62#include "intel_fbc.h"
63#include "intel_frontbuffer.h"
64#include "intel_psr.h"
65
66/**
67 * frontbuffer_flush - flush frontbuffer
68 * @i915: i915 device
69 * @frontbuffer_bits: frontbuffer plane tracking bits
70 * @origin: which operation caused the flush
71 *
72 * This function gets called every time rendering on the given planes has
73 * completed and frontbuffer caching can be started again. Flushes will get
74 * delayed if they're blocked by some outstanding asynchronous rendering.
75 *
76 * Can be called without any locks held.
77 */
78static void frontbuffer_flush(struct drm_i915_private *i915,
79 unsigned int frontbuffer_bits,
80 enum fb_op_origin origin)
81{
82 /* Delay flushing when rings are still busy.*/
83 spin_lock(&i915->fb_tracking.lock);
84 frontbuffer_bits &= ~i915->fb_tracking.busy_bits;
85 spin_unlock(&i915->fb_tracking.lock);
86
87 if (!frontbuffer_bits)
88 return;
89
90 might_sleep();
91 intel_edp_drrs_flush(i915, frontbuffer_bits);
92 intel_psr_flush(i915, frontbuffer_bits, origin);
93 intel_fbc_flush(i915, frontbuffer_bits, origin);
94}
95
96/**
97 * intel_frontbuffer_flip_prepare - prepare asynchronous frontbuffer flip
98 * @i915: i915 device
99 * @frontbuffer_bits: frontbuffer plane tracking bits
100 *
101 * This function gets called after scheduling a flip on @obj. The actual
102 * frontbuffer flushing will be delayed until completion is signalled with
103 * intel_frontbuffer_flip_complete. If an invalidate happens in between this
104 * flush will be cancelled.
105 *
106 * Can be called without any locks held.
107 */
108void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915,
109 unsigned frontbuffer_bits)
110{
111 spin_lock(&i915->fb_tracking.lock);
112 i915->fb_tracking.flip_bits |= frontbuffer_bits;
113 /* Remove stale busy bits due to the old buffer. */
114 i915->fb_tracking.busy_bits &= ~frontbuffer_bits;
115 spin_unlock(&i915->fb_tracking.lock);
116}
117
118/**
119 * intel_frontbuffer_flip_complete - complete asynchronous frontbuffer flip
120 * @i915: i915 device
121 * @frontbuffer_bits: frontbuffer plane tracking bits
122 *
123 * This function gets called after the flip has been latched and will complete
124 * on the next vblank. It will execute the flush if it hasn't been cancelled yet.
125 *
126 * Can be called without any locks held.
127 */
128void intel_frontbuffer_flip_complete(struct drm_i915_private *i915,
129 unsigned frontbuffer_bits)
130{
131 spin_lock(&i915->fb_tracking.lock);
132 /* Mask any cancelled flips. */
133 frontbuffer_bits &= i915->fb_tracking.flip_bits;
134 i915->fb_tracking.flip_bits &= ~frontbuffer_bits;
135 spin_unlock(&i915->fb_tracking.lock);
136
137 if (frontbuffer_bits)
138 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
139}
140
141/**
142 * intel_frontbuffer_flip - synchronous frontbuffer flip
143 * @i915: i915 device
144 * @frontbuffer_bits: frontbuffer plane tracking bits
145 *
146 * This function gets called after scheduling a flip on @obj. This is for
147 * synchronous plane updates which will happen on the next vblank and which will
148 * not get delayed by pending gpu rendering.
149 *
150 * Can be called without any locks held.
151 */
152void intel_frontbuffer_flip(struct drm_i915_private *i915,
153 unsigned frontbuffer_bits)
154{
155 spin_lock(&i915->fb_tracking.lock);
156 /* Remove stale busy bits due to the old buffer. */
157 i915->fb_tracking.busy_bits &= ~frontbuffer_bits;
158 spin_unlock(&i915->fb_tracking.lock);
159
160 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP);
161}
162
163void __intel_fb_invalidate(struct intel_frontbuffer *front,
164 enum fb_op_origin origin,
165 unsigned int frontbuffer_bits)
166{
167 struct drm_i915_private *i915 = to_i915(front->obj->base.dev);
168
169 if (origin == ORIGIN_CS) {
170 spin_lock(&i915->fb_tracking.lock);
171 i915->fb_tracking.busy_bits |= frontbuffer_bits;
172 i915->fb_tracking.flip_bits &= ~frontbuffer_bits;
173 spin_unlock(&i915->fb_tracking.lock);
174 }
175
176 might_sleep();
177 intel_psr_invalidate(i915, frontbuffer_bits, origin);
178 intel_edp_drrs_invalidate(i915, frontbuffer_bits);
179 intel_fbc_invalidate(i915, frontbuffer_bits, origin);
180}
181
182void __intel_fb_flush(struct intel_frontbuffer *front,
183 enum fb_op_origin origin,
184 unsigned int frontbuffer_bits)
185{
186 struct drm_i915_private *i915 = to_i915(front->obj->base.dev);
187
188 if (origin == ORIGIN_CS) {
189 spin_lock(&i915->fb_tracking.lock);
190 /* Filter out new bits since rendering started. */
191 frontbuffer_bits &= i915->fb_tracking.busy_bits;
192 i915->fb_tracking.busy_bits &= ~frontbuffer_bits;
193 spin_unlock(&i915->fb_tracking.lock);
194 }
195
196 if (frontbuffer_bits)
197 frontbuffer_flush(i915, frontbuffer_bits, origin);
198}
199
200static int frontbuffer_active(struct i915_active *ref)
201{
202 struct intel_frontbuffer *front =
203 container_of(ref, typeof(*front), write);
204
205 kref_get(&front->ref);
206 return 0;
207}
208
209__i915_active_call
210static void frontbuffer_retire(struct i915_active *ref)
211{
212 struct intel_frontbuffer *front =
213 container_of(ref, typeof(*front), write);
214
215 intel_frontbuffer_flush(front, ORIGIN_CS);
216 intel_frontbuffer_put(front);
217}
218
219static void frontbuffer_release(struct kref *ref)
220 __releases(&to_i915(front->obj->base.dev)->fb_tracking.lock)
221{
222 struct intel_frontbuffer *front =
223 container_of(ref, typeof(*front), ref);
224 struct drm_i915_gem_object *obj = front->obj;
225 struct i915_vma *vma;
226
227 spin_lock(&obj->vma.lock);
228 for_each_ggtt_vma(vma, obj)
229 vma->display_alignment = I915_GTT_MIN_ALIGNMENT;
230 spin_unlock(&obj->vma.lock);
231
232 RCU_INIT_POINTER(obj->frontbuffer, NULL);
233 spin_unlock(&to_i915(obj->base.dev)->fb_tracking.lock);
234
235 i915_gem_object_put(obj);
236 kfree_rcu(front, rcu);
237}
238
239struct intel_frontbuffer *
240intel_frontbuffer_get(struct drm_i915_gem_object *obj)
241{
242 struct drm_i915_private *i915 = to_i915(obj->base.dev);
243 struct intel_frontbuffer *front;
244
245 front = __intel_frontbuffer_get(obj);
246 if (front)
247 return front;
248
249 front = kmalloc(sizeof(*front), GFP_KERNEL);
250 if (!front)
251 return NULL;
252
253 front->obj = obj;
254 kref_init(&front->ref);
255 atomic_set(&front->bits, 0);
256 i915_active_init(&front->write,
257 frontbuffer_active,
258 i915_active_may_sleep(frontbuffer_retire));
259
260 spin_lock(&i915->fb_tracking.lock);
261 if (rcu_access_pointer(obj->frontbuffer)) {
262 kfree(front);
263 front = rcu_dereference_protected(obj->frontbuffer, true);
264 kref_get(&front->ref);
265 } else {
266 i915_gem_object_get(obj);
267 rcu_assign_pointer(obj->frontbuffer, front);
268 }
269 spin_unlock(&i915->fb_tracking.lock);
270
271 return front;
272}
273
274void intel_frontbuffer_put(struct intel_frontbuffer *front)
275{
276 kref_put_lock(&front->ref,
277 frontbuffer_release,
278 &to_i915(front->obj->base.dev)->fb_tracking.lock);
279}
280
281/**
282 * intel_frontbuffer_track - update frontbuffer tracking
283 * @old: current buffer for the frontbuffer slots
284 * @new: new buffer for the frontbuffer slots
285 * @frontbuffer_bits: bitmask of frontbuffer slots
286 *
287 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
288 * from @old and setting them in @new. Both @old and @new can be NULL.
289 */
290void intel_frontbuffer_track(struct intel_frontbuffer *old,
291 struct intel_frontbuffer *new,
292 unsigned int frontbuffer_bits)
293{
294 /*
295 * Control of individual bits within the mask are guarded by
296 * the owning plane->mutex, i.e. we can never see concurrent
297 * manipulation of individual bits. But since the bitfield as a whole
298 * is updated using RMW, we need to use atomics in order to update
299 * the bits.
300 */
301 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
302 BITS_PER_TYPE(atomic_t));
303
304 if (old) {
305 drm_WARN_ON(old->obj->base.dev,
306 !(atomic_read(&old->bits) & frontbuffer_bits));
307 atomic_andnot(frontbuffer_bits, &old->bits);
308 }
309
310 if (new) {
311 drm_WARN_ON(new->obj->base.dev,
312 atomic_read(&new->bits) & frontbuffer_bits);
313 atomic_or(frontbuffer_bits, &new->bits);
314 }
315}