intel_frontbuffer.c

  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 <drm/drm_gem.h>
 59#include <drm/drm_print.h>
 60
 61#include "intel_bo.h"
 62#include "intel_display_trace.h"
 63#include "intel_display_types.h"
 64#include "intel_dp.h"
 65#include "intel_drrs.h"
 66#include "intel_fbc.h"
 67#include "intel_frontbuffer.h"
 68#include "intel_psr.h"
 69#include "intel_tdf.h"
 70
 71/**
 72 * frontbuffer_flush - flush frontbuffer
 73 * @display: display device
 74 * @frontbuffer_bits: frontbuffer plane tracking bits
 75 * @origin: which operation caused the flush
 76 *
 77 * This function gets called every time rendering on the given planes has
 78 * completed and frontbuffer caching can be started again. Flushes will get
 79 * delayed if they're blocked by some outstanding asynchronous rendering.
 80 *
 81 * Can be called without any locks held.
 82 */
 83static void frontbuffer_flush(struct intel_display *display,
 84			      unsigned int frontbuffer_bits,
 85			      enum fb_op_origin origin)
 86{
 87	/* Delay flushing when rings are still busy.*/
 88	spin_lock(&display->fb_tracking.lock);
 89	frontbuffer_bits &= ~display->fb_tracking.busy_bits;
 90	spin_unlock(&display->fb_tracking.lock);
 91
 92	if (!frontbuffer_bits)
 93		return;
 94
 95	trace_intel_frontbuffer_flush(display, frontbuffer_bits, origin);
 96
 97	might_sleep();
 98	intel_td_flush(display);
 99	intel_drrs_flush(display, frontbuffer_bits);
100	intel_psr_flush(display, frontbuffer_bits, origin);
101	intel_fbc_flush(display, frontbuffer_bits, origin);
102}
103
104/**
105 * intel_frontbuffer_flip - synchronous frontbuffer flip
106 * @display: display device
107 * @frontbuffer_bits: frontbuffer plane tracking bits
108 *
109 * This function gets called after scheduling a flip on @obj. This is for
110 * synchronous plane updates which will happen on the next vblank and which will
111 * not get delayed by pending gpu rendering.
112 *
113 * Can be called without any locks held.
114 */
115void intel_frontbuffer_flip(struct intel_display *display,
116			    unsigned frontbuffer_bits)
117{
118	spin_lock(&display->fb_tracking.lock);
119	/* Remove stale busy bits due to the old buffer. */
120	display->fb_tracking.busy_bits &= ~frontbuffer_bits;
121	spin_unlock(&display->fb_tracking.lock);
122
123	frontbuffer_flush(display, frontbuffer_bits, ORIGIN_FLIP);
124}
125
126void __intel_fb_invalidate(struct intel_frontbuffer *front,
127			   enum fb_op_origin origin,
128			   unsigned int frontbuffer_bits)
129{
130	struct intel_display *display = front->display;
131
132	if (origin == ORIGIN_CS) {
133		spin_lock(&display->fb_tracking.lock);
134		display->fb_tracking.busy_bits |= frontbuffer_bits;
135		spin_unlock(&display->fb_tracking.lock);
136	}
137
138	trace_intel_frontbuffer_invalidate(display, frontbuffer_bits, origin);
139
140	might_sleep();
141	intel_psr_invalidate(display, frontbuffer_bits, origin);
142	intel_drrs_invalidate(display, frontbuffer_bits);
143	intel_fbc_invalidate(display, frontbuffer_bits, origin);
144}
145
146void __intel_fb_flush(struct intel_frontbuffer *front,
147		      enum fb_op_origin origin,
148		      unsigned int frontbuffer_bits)
149{
150	struct intel_display *display = front->display;
151
152	if (origin == ORIGIN_DIRTYFB)
153		intel_bo_frontbuffer_flush_for_display(front);
154
155	if (origin == ORIGIN_CS) {
156		spin_lock(&display->fb_tracking.lock);
157		/* Filter out new bits since rendering started. */
158		frontbuffer_bits &= display->fb_tracking.busy_bits;
159		display->fb_tracking.busy_bits &= ~frontbuffer_bits;
160		spin_unlock(&display->fb_tracking.lock);
161	}
162
163	if (frontbuffer_bits)
164		frontbuffer_flush(display, frontbuffer_bits, origin);
165}
166
167static void intel_frontbuffer_ref(struct intel_frontbuffer *front)
168{
169	intel_bo_frontbuffer_ref(front);
170}
171
172static void intel_frontbuffer_flush_work(struct work_struct *work)
173{
174	struct intel_frontbuffer *front =
175		container_of(work, struct intel_frontbuffer, flush_work);
176
177	intel_frontbuffer_flush(front, ORIGIN_DIRTYFB);
178	intel_frontbuffer_put(front);
179}
180
181/**
182 * intel_frontbuffer_queue_flush - queue flushing frontbuffer object
183 * @front: GEM object to flush
184 *
185 * This function is targeted for our dirty callback for queueing flush when
186 * dma fence is signals
187 */
188void intel_frontbuffer_queue_flush(struct intel_frontbuffer *front)
189{
190	if (!front)
191		return;
192
193	intel_frontbuffer_ref(front);
194	if (!schedule_work(&front->flush_work))
195		intel_frontbuffer_put(front);
196}
197
198void intel_frontbuffer_init(struct intel_frontbuffer *front, struct drm_device *drm)
199{
200	front->display = to_intel_display(drm);
201	atomic_set(&front->bits, 0);
202	INIT_WORK(&front->flush_work, intel_frontbuffer_flush_work);
203}
204
205void intel_frontbuffer_fini(struct intel_frontbuffer *front)
206{
207	drm_WARN_ON(front->display->drm, atomic_read(&front->bits));
208}
209
210struct intel_frontbuffer *intel_frontbuffer_get(struct drm_gem_object *obj)
211{
212	return intel_bo_frontbuffer_get(obj);
213}
214
215void intel_frontbuffer_put(struct intel_frontbuffer *front)
216{
217	intel_bo_frontbuffer_put(front);
218}
219
220/**
221 * intel_frontbuffer_track - update frontbuffer tracking
222 * @old: current buffer for the frontbuffer slots
223 * @new: new buffer for the frontbuffer slots
224 * @frontbuffer_bits: bitmask of frontbuffer slots
225 *
226 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
227 * from @old and setting them in @new. Both @old and @new can be NULL.
228 */
229void intel_frontbuffer_track(struct intel_frontbuffer *old,
230			     struct intel_frontbuffer *new,
231			     unsigned int frontbuffer_bits)
232{
233	/*
234	 * Control of individual bits within the mask are guarded by
235	 * the owning plane->mutex, i.e. we can never see concurrent
236	 * manipulation of individual bits. But since the bitfield as a whole
237	 * is updated using RMW, we need to use atomics in order to update
238	 * the bits.
239	 */
240	BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
241		     BITS_PER_TYPE(atomic_t));
242	BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 32);
243	BUILD_BUG_ON(I915_MAX_PLANES > INTEL_FRONTBUFFER_BITS_PER_PIPE);
244
245	if (old) {
246		drm_WARN_ON(old->display->drm,
247			    !(atomic_read(&old->bits) & frontbuffer_bits));
248		atomic_andnot(frontbuffer_bits, &old->bits);
249	}
250
251	if (new) {
252		drm_WARN_ON(new->display->drm,
253			    atomic_read(&new->bits) & frontbuffer_bits);
254		atomic_or(frontbuffer_bits, &new->bits);
255	}
256}