drivers/gpu/drm/msm/msm_atomic.c

   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_atomic_state *state;
  24         uint32_t fence;
  25         struct msm_fence_cb fence_cb;
  26         uint32_t crtc_mask;
  27 };
  28
  29 static void fence_cb(struct msm_fence_cb *cb);
  30
  31 /* block until specified crtcs are no longer pending update, and
  32  * atomically mark them as pending update
  33  */
  34 static int start_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
  35 {
  36         int ret;
  37
  38         spin_lock(&priv->pending_crtcs_event.lock);
  39         ret = wait_event_interruptible_locked(priv->pending_crtcs_event,
  40                         !(priv->pending_crtcs & crtc_mask));
  41         if (ret == 0) {
  42                 DBG("start: %08x", crtc_mask);
  43                 priv->pending_crtcs |= crtc_mask;
  44         }
  45         spin_unlock(&priv->pending_crtcs_event.lock);
  46
  47         return ret;
  48 }
  49
  50 /* clear specified crtcs (no longer pending update)
  51  */
  52 static void end_atomic(struct msm_drm_private *priv, uint32_t crtc_mask)
  53 {
  54         spin_lock(&priv->pending_crtcs_event.lock);
  55         DBG("end: %08x", crtc_mask);
  56         priv->pending_crtcs &= ~crtc_mask;
  57         wake_up_all_locked(&priv->pending_crtcs_event);
  58         spin_unlock(&priv->pending_crtcs_event.lock);
  59 }
  60
  61 static struct msm_commit *new_commit(struct drm_atomic_state *state)
  62 {
  63         struct msm_commit *c = kzalloc(sizeof(*c), GFP_KERNEL);
  64
  65         if (!c)
  66                 return NULL;
  67
  68         c->state = state;
  69         /* TODO we might need a way to indicate to run the cb on a
  70          * different wq so wait_for_vblanks() doesn't block retiring
  71          * bo's..
  72          */
  73         INIT_FENCE_CB(&c->fence_cb, fence_cb);
  74
  75         return c;
  76 }
  77
  78 /* The (potentially) asynchronous part of the commit.  At this point
  79  * nothing can fail short of armageddon.
  80  */
  81 static void complete_commit(struct msm_commit *c)
  82 {
  83         struct drm_atomic_state *state = c->state;
  84         struct drm_device *dev = state->dev;
  85
  86         drm_atomic_helper_commit_pre_planes(dev, state);
  87
  88         drm_atomic_helper_commit_planes(dev, state);
  89
  90         drm_atomic_helper_commit_post_planes(dev, state);
  91
  92         /* NOTE: _wait_for_vblanks() only waits for vblank on
  93          * enabled CRTCs.  So we end up faulting when disabling
  94          * due to (potentially) unref'ing the outgoing fb's
  95          * before the vblank when the disable has latched.
  96          *
  97          * But if it did wait on disabled (or newly disabled)
  98          * CRTCs, that would be racy (ie. we could have missed
  99          * the irq.  We need some way to poll for pipe shut
 100          * down.  Or just live with occasionally hitting the
 101          * timeout in the CRTC disable path (which really should
 102          * not be critical path)
 103          */
 104
 105         drm_atomic_helper_wait_for_vblanks(dev, state);
 106
 107         drm_atomic_helper_cleanup_planes(dev, state);
 108
 109         drm_atomic_state_free(state);
 110
 111         end_atomic(dev->dev_private, c->crtc_mask);
 112
 113         kfree(c);
 114 }
 115
 116 static void fence_cb(struct msm_fence_cb *cb)
 117 {
 118         struct msm_commit *c =
 119                         container_of(cb, struct msm_commit, fence_cb);
 120         complete_commit(c);
 121 }
 122
 123 static void add_fb(struct msm_commit *c, struct drm_framebuffer *fb)
 124 {
 125         struct drm_gem_object *obj = msm_framebuffer_bo(fb, 0);
 126         c->fence = max(c->fence, msm_gem_fence(to_msm_bo(obj), MSM_PREP_READ));
 127 }
 128
 129
 130 /**
 131  * drm_atomic_helper_commit - commit validated state object
 132  * @dev: DRM device
 133  * @state: the driver state object
 134  * @async: asynchronous commit
 135  *
 136  * This function commits a with drm_atomic_helper_check() pre-validated state
 137  * object. This can still fail when e.g. the framebuffer reservation fails. For
 138  * now this doesn't implement asynchronous commits.
 139  *
 140  * RETURNS
 141  * Zero for success or -errno.
 142  */
 143 int msm_atomic_commit(struct drm_device *dev,
 144                 struct drm_atomic_state *state, bool async)
 145 {
 146         int nplanes = dev->mode_config.num_total_plane;
 147         int ncrtcs = dev->mode_config.num_crtc;
 148         struct msm_commit *c;
 149         int i, ret;
 150
 151         ret = drm_atomic_helper_prepare_planes(dev, state);
 152         if (ret)
 153                 return ret;
 154
 155         c = new_commit(state);
 156         if (!c)
 157                 return -ENOMEM;
 158
 159         /*
 160          * Figure out what crtcs we have:
 161          */
 162         for (i = 0; i < ncrtcs; i++) {
 163                 struct drm_crtc *crtc = state->crtcs[i];
 164                 if (!crtc)
 165                         continue;
 166                 c->crtc_mask |= (1 << drm_crtc_index(crtc));
 167         }
 168
 169         /*
 170          * Figure out what fence to wait for:
 171          */
 172         for (i = 0; i < nplanes; i++) {
 173                 struct drm_plane *plane = state->planes[i];
 174                 struct drm_plane_state *new_state = state->plane_states[i];
 175
 176                 if (!plane)
 177                         continue;
 178
 179                 if ((plane->state->fb != new_state->fb) && new_state->fb)
 180                         add_fb(c, new_state->fb);
 181         }
 182
 183         /*
 184          * Wait for pending updates on any of the same crtc's and then
 185          * mark our set of crtc's as busy:
 186          */
 187         ret = start_atomic(dev->dev_private, c->crtc_mask);
 188         if (ret)
 189                 return ret;
 190
 191         /*
 192          * This is the point of no return - everything below never fails except
 193          * when the hw goes bonghits. Which means we can commit the new state on
 194          * the software side now.
 195          */
 196
 197         drm_atomic_helper_swap_state(dev, state);
 198
 199         /*
 200          * Everything below can be run asynchronously without the need to grab
 201          * any modeset locks at all under one conditions: It must be guaranteed
 202          * that the asynchronous work has either been cancelled (if the driver
 203          * supports it, which at least requires that the framebuffers get
 204          * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
 205          * before the new state gets committed on the software side with
 206          * drm_atomic_helper_swap_state().
 207          *
 208          * This scheme allows new atomic state updates to be prepared and
 209          * checked in parallel to the asynchronous completion of the previous
 210          * update. Which is important since compositors need to figure out the
 211          * composition of the next frame right after having submitted the
 212          * current layout.
 213          */
 214
 215         if (async) {
 216                 msm_queue_fence_cb(dev, &c->fence_cb, c->fence);
 217                 return 0;
 218         }
 219
 220         ret = msm_wait_fence_interruptable(dev, c->fence, NULL);
 221         if (ret) {
 222                 WARN_ON(ret);  // TODO unswap state back?  or??
 223                 kfree(c);
 224                 return ret;
 225         }
 226
 227         complete_commit(c);
 228
 229         return 0;
 230 }