xref: /openbmc/linux/drivers/gpu/drm/msm/msm_atomic.c (revision abfbd895)
1 /*
2  * Copyright (C) 2014 Red Hat
3  * Author: Rob Clark <robdclark@gmail.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 as published by
7  * the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  * You should have received a copy of the GNU General Public License along with
15  * this program.  If not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 #include "msm_drv.h"
19 #include "msm_kms.h"
20 #include "msm_gem.h"
21 
22 struct msm_commit {
23 	struct drm_device *dev;
24 	struct drm_atomic_state *state;
25 	uint32_t fence;
26 	struct msm_fence_cb fence_cb;
27 	uint32_t crtc_mask;
28 };
29 
30 static void fence_cb(struct msm_fence_cb *cb);
31 
32 /* block until specified crtcs are no longer pending update, and
33  * atomically mark them as pending update
34  */
35 static int start_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
36 {
37 	int ret;
38 
39 	spin_lock(&priv->pending_crtcs_event.lock);
40 	ret = wait_event_interruptible_locked(priv->pending_crtcs_event,
41 			!(priv->pending_crtcs & crtc_mask));
42 	if (ret == 0) {
43 		DBG("start: %08x", crtc_mask);
44 		priv->pending_crtcs |= crtc_mask;
45 	}
46 	spin_unlock(&priv->pending_crtcs_event.lock);
47 
48 	return ret;
49 }
50 
51 /* clear specified crtcs (no longer pending update)
52  */
53 static void end_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
54 {
55 	spin_lock(&priv->pending_crtcs_event.lock);
56 	DBG("end: %08x", crtc_mask);
57 	priv->pending_crtcs &= ~crtc_mask;
58 	wake_up_all_locked(&priv->pending_crtcs_event);
59 	spin_unlock(&priv->pending_crtcs_event.lock);
60 }
61 
62 static struct msm_commit *commit_init(struct drm_atomic_state *state)
63 {
64 	struct msm_commit *c = kzalloc(sizeof(*c), GFP_KERNEL);
65 
66 	if (!c)
67 		return NULL;
68 
69 	c->dev = state->dev;
70 	c->state = state;
71 
72 	/* TODO we might need a way to indicate to run the cb on a
73 	 * different wq so wait_for_vblanks() doesn't block retiring
74 	 * bo's..
75 	 */
76 	INIT_FENCE_CB(&c->fence_cb, fence_cb);
77 
78 	return c;
79 }
80 
81 static void commit_destroy(struct msm_commit *c)
82 {
83 	end_atomic(c->dev->dev_private, c->crtc_mask);
84 	kfree(c);
85 }
86 
87 static void msm_atomic_wait_for_commit_done(struct drm_device *dev,
88 		struct drm_atomic_state *old_state)
89 {
90 	struct drm_crtc *crtc;
91 	struct msm_drm_private *priv = old_state->dev->dev_private;
92 	struct msm_kms *kms = priv->kms;
93 	int ncrtcs = old_state->dev->mode_config.num_crtc;
94 	int i;
95 
96 	for (i = 0; i < ncrtcs; i++) {
97 		crtc = old_state->crtcs[i];
98 
99 		if (!crtc)
100 			continue;
101 
102 		if (!crtc->state->enable)
103 			continue;
104 
105 		/* Legacy cursor ioctls are completely unsynced, and userspace
106 		 * relies on that (by doing tons of cursor updates). */
107 		if (old_state->legacy_cursor_update)
108 			continue;
109 
110 		kms->funcs->wait_for_crtc_commit_done(kms, crtc);
111 	}
112 }
113 
114 /* The (potentially) asynchronous part of the commit.  At this point
115  * nothing can fail short of armageddon.
116  */
117 static void complete_commit(struct msm_commit *c)
118 {
119 	struct drm_atomic_state *state = c->state;
120 	struct drm_device *dev = state->dev;
121 	struct msm_drm_private *priv = dev->dev_private;
122 	struct msm_kms *kms = priv->kms;
123 
124 	kms->funcs->prepare_commit(kms, state);
125 
126 	drm_atomic_helper_commit_modeset_disables(dev, state);
127 
128 	drm_atomic_helper_commit_planes(dev, state, false);
129 
130 	drm_atomic_helper_commit_modeset_enables(dev, state);
131 
132 	/* NOTE: _wait_for_vblanks() only waits for vblank on
133 	 * enabled CRTCs.  So we end up faulting when disabling
134 	 * due to (potentially) unref'ing the outgoing fb's
135 	 * before the vblank when the disable has latched.
136 	 *
137 	 * But if it did wait on disabled (or newly disabled)
138 	 * CRTCs, that would be racy (ie. we could have missed
139 	 * the irq.  We need some way to poll for pipe shut
140 	 * down.  Or just live with occasionally hitting the
141 	 * timeout in the CRTC disable path (which really should
142 	 * not be critical path)
143 	 */
144 
145 	msm_atomic_wait_for_commit_done(dev, state);
146 
147 	drm_atomic_helper_cleanup_planes(dev, state);
148 
149 	kms->funcs->complete_commit(kms, state);
150 
151 	drm_atomic_state_free(state);
152 
153 	commit_destroy(c);
154 }
155 
156 static void fence_cb(struct msm_fence_cb *cb)
157 {
158 	struct msm_commit *c =
159 			container_of(cb, struct msm_commit, fence_cb);
160 	complete_commit(c);
161 }
162 
163 static void add_fb(struct msm_commit *c, struct drm_framebuffer *fb)
164 {
165 	struct drm_gem_object *obj = msm_framebuffer_bo(fb, 0);
166 	c->fence = max(c->fence, msm_gem_fence(to_msm_bo(obj), MSM_PREP_READ));
167 }
168 
169 int msm_atomic_check(struct drm_device *dev,
170 		     struct drm_atomic_state *state)
171 {
172 	int ret;
173 
174 	/*
175 	 * msm ->atomic_check can update ->mode_changed for pixel format
176 	 * changes, hence must be run before we check the modeset changes.
177 	 */
178 	ret = drm_atomic_helper_check_planes(dev, state);
179 	if (ret)
180 		return ret;
181 
182 	ret = drm_atomic_helper_check_modeset(dev, state);
183 	if (ret)
184 		return ret;
185 
186 	return ret;
187 }
188 
189 /**
190  * drm_atomic_helper_commit - commit validated state object
191  * @dev: DRM device
192  * @state: the driver state object
193  * @async: asynchronous commit
194  *
195  * This function commits a with drm_atomic_helper_check() pre-validated state
196  * object. This can still fail when e.g. the framebuffer reservation fails. For
197  * now this doesn't implement asynchronous commits.
198  *
199  * RETURNS
200  * Zero for success or -errno.
201  */
202 int msm_atomic_commit(struct drm_device *dev,
203 		struct drm_atomic_state *state, bool async)
204 {
205 	int nplanes = dev->mode_config.num_total_plane;
206 	int ncrtcs = dev->mode_config.num_crtc;
207 	ktime_t timeout;
208 	struct msm_commit *c;
209 	int i, ret;
210 
211 	ret = drm_atomic_helper_prepare_planes(dev, state);
212 	if (ret)
213 		return ret;
214 
215 	c = commit_init(state);
216 	if (!c) {
217 		ret = -ENOMEM;
218 		goto error;
219 	}
220 
221 	/*
222 	 * Figure out what crtcs we have:
223 	 */
224 	for (i = 0; i < ncrtcs; i++) {
225 		struct drm_crtc *crtc = state->crtcs[i];
226 		if (!crtc)
227 			continue;
228 		c->crtc_mask |= (1 << drm_crtc_index(crtc));
229 	}
230 
231 	/*
232 	 * Figure out what fence to wait for:
233 	 */
234 	for (i = 0; i < nplanes; i++) {
235 		struct drm_plane *plane = state->planes[i];
236 		struct drm_plane_state *new_state = state->plane_states[i];
237 
238 		if (!plane)
239 			continue;
240 
241 		if ((plane->state->fb != new_state->fb) && new_state->fb)
242 			add_fb(c, new_state->fb);
243 	}
244 
245 	/*
246 	 * Wait for pending updates on any of the same crtc's and then
247 	 * mark our set of crtc's as busy:
248 	 */
249 	ret = start_atomic(dev->dev_private, c->crtc_mask);
250 	if (ret) {
251 		kfree(c);
252 		goto error;
253 	}
254 
255 	/*
256 	 * This is the point of no return - everything below never fails except
257 	 * when the hw goes bonghits. Which means we can commit the new state on
258 	 * the software side now.
259 	 */
260 
261 	drm_atomic_helper_swap_state(dev, state);
262 
263 	/*
264 	 * Everything below can be run asynchronously without the need to grab
265 	 * any modeset locks at all under one conditions: It must be guaranteed
266 	 * that the asynchronous work has either been cancelled (if the driver
267 	 * supports it, which at least requires that the framebuffers get
268 	 * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
269 	 * before the new state gets committed on the software side with
270 	 * drm_atomic_helper_swap_state().
271 	 *
272 	 * This scheme allows new atomic state updates to be prepared and
273 	 * checked in parallel to the asynchronous completion of the previous
274 	 * update. Which is important since compositors need to figure out the
275 	 * composition of the next frame right after having submitted the
276 	 * current layout.
277 	 */
278 
279 	if (async) {
280 		msm_queue_fence_cb(dev, &c->fence_cb, c->fence);
281 		return 0;
282 	}
283 
284 	timeout = ktime_add_ms(ktime_get(), 1000);
285 
286 	/* uninterruptible wait */
287 	msm_wait_fence(dev, c->fence, &timeout, false);
288 
289 	complete_commit(c);
290 
291 	return 0;
292 
293 error:
294 	drm_atomic_helper_cleanup_planes(dev, state);
295 	return ret;
296 }
297