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 */
78 static 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 */
108 void 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 */
128 void 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 */
152 void 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
163 void __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
182 void __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
200 static 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 static void frontbuffer_retire(struct i915_active *ref)
210 {
211 struct intel_frontbuffer *front =
212 container_of(ref, typeof(*front), write);
213
214 intel_frontbuffer_flush(front, ORIGIN_CS);
215 intel_frontbuffer_put(front);
216 }
217
218 static void frontbuffer_release(struct kref *ref)
219 __releases(&to_i915(front->obj->base.dev)->fb_tracking.lock)
220 {
221 struct intel_frontbuffer *front =
222 container_of(ref, typeof(*front), ref);
223
224 front->obj->frontbuffer = NULL;
225 spin_unlock(&to_i915(front->obj->base.dev)->fb_tracking.lock);
226
227 i915_gem_object_put(front->obj);
228 kfree(front);
229 }
230
231 struct intel_frontbuffer *
232 intel_frontbuffer_get(struct drm_i915_gem_object *obj)
233 {
234 struct drm_i915_private *i915 = to_i915(obj->base.dev);
235 struct intel_frontbuffer *front;
236
237 spin_lock(&i915->fb_tracking.lock);
238 front = obj->frontbuffer;
239 if (front)
240 kref_get(&front->ref);
241 spin_unlock(&i915->fb_tracking.lock);
242 if (front)
243 return front;
244
245 front = kmalloc(sizeof(*front), GFP_KERNEL);
246 if (!front)
247 return NULL;
248
249 front->obj = obj;
250 kref_init(&front->ref);
251 atomic_set(&front->bits, 0);
252 i915_active_init(i915, &front->write,
253 frontbuffer_active, frontbuffer_retire);
254
255 spin_lock(&i915->fb_tracking.lock);
256 if (obj->frontbuffer) {
257 kfree(front);
258 front = obj->frontbuffer;
259 kref_get(&front->ref);
260 } else {
261 i915_gem_object_get(obj);
262 obj->frontbuffer = front;
263 }
264 spin_unlock(&i915->fb_tracking.lock);
265
266 return front;
267 }
268
269 void intel_frontbuffer_put(struct intel_frontbuffer *front)
270 {
271 kref_put_lock(&front->ref,
272 frontbuffer_release,
273 &to_i915(front->obj->base.dev)->fb_tracking.lock);
274 }
275
276 /**
277 * intel_frontbuffer_track - update frontbuffer tracking
278 * @old: current buffer for the frontbuffer slots
279 * @new: new buffer for the frontbuffer slots
280 * @frontbuffer_bits: bitmask of frontbuffer slots
281 *
282 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
283 * from @old and setting them in @new. Both @old and @new can be NULL.
284 */
285 void intel_frontbuffer_track(struct intel_frontbuffer *old,
286 struct intel_frontbuffer *new,
287 unsigned int frontbuffer_bits)
288 {
289 /*
290 * Control of individual bits within the mask are guarded by
291 * the owning plane->mutex, i.e. we can never see concurrent
292 * manipulation of individual bits. But since the bitfield as a whole
293 * is updated using RMW, we need to use atomics in order to update
294 * the bits.
295 */
296 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
297 BITS_PER_TYPE(atomic_t));
298
299 if (old) {
300 WARN_ON(!(atomic_read(&old->bits) & frontbuffer_bits));
301 atomic_andnot(frontbuffer_bits, &old->bits);
302 }
303
304 if (new) {
305 WARN_ON(atomic_read(&new->bits) & frontbuffer_bits);
306 atomic_or(frontbuffer_bits, &new->bits);
307 }
308 }