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 };
  27
  28 static void fence_cb(struct msm_fence_cb *cb);
  29
  30 static struct msm_commit *new_commit(struct drm_atomic_state *state)
  31 {
  32         struct msm_commit *c = kzalloc(sizeof(*c), GFP_KERNEL);
  33
  34         if (!c)
  35                 return NULL;
  36
  37         c->state = state;
  38         /* TODO we might need a way to indicate to run the cb on a
  39          * different wq so wait_for_vblanks() doesn't block retiring
  40          * bo's..
  41          */
  42         INIT_FENCE_CB(&c->fence_cb, fence_cb);
  43
  44         return c;
  45 }
  46
  47 /* The (potentially) asynchronous part of the commit.  At this point
  48  * nothing can fail short of armageddon.
  49  */
  50 static void complete_commit(struct msm_commit *c)
  51 {
  52         struct drm_atomic_state *state = c->state;
  53         struct drm_device *dev = state->dev;
  54
  55         drm_atomic_helper_commit_pre_planes(dev, state);
  56
  57         drm_atomic_helper_commit_planes(dev, state);
  58
  59         drm_atomic_helper_commit_post_planes(dev, state);
  60
  61         drm_atomic_helper_wait_for_vblanks(dev, state);
  62
  63         drm_atomic_helper_cleanup_planes(dev, state);
  64
  65         drm_atomic_state_free(state);
  66
  67         kfree(c);
  68 }
  69
  70 static void fence_cb(struct msm_fence_cb *cb)
  71 {
  72         struct msm_commit *c =
  73                         container_of(cb, struct msm_commit, fence_cb);
  74         complete_commit(c);
  75 }
  76
  77 static void add_fb(struct msm_commit *c, struct drm_framebuffer *fb)
  78 {
  79         struct drm_gem_object *obj = msm_framebuffer_bo(fb, 0);
  80         c->fence = max(c->fence, msm_gem_fence(to_msm_bo(obj), MSM_PREP_READ));
  81 }
  82
  83
  84 /**
  85  * drm_atomic_helper_commit - commit validated state object
  86  * @dev: DRM device
  87  * @state: the driver state object
  88  * @async: asynchronous commit
  89  *
  90  * This function commits a with drm_atomic_helper_check() pre-validated state
  91  * object. This can still fail when e.g. the framebuffer reservation fails. For
  92  * now this doesn't implement asynchronous commits.
  93  *
  94  * RETURNS
  95  * Zero for success or -errno.
  96  */
  97 int msm_atomic_commit(struct drm_device *dev,
  98                 struct drm_atomic_state *state, bool async)
  99 {
 100         struct msm_commit *c;
 101         int nplanes = dev->mode_config.num_total_plane;
 102         int i, ret;
 103
 104         ret = drm_atomic_helper_prepare_planes(dev, state);
 105         if (ret)
 106                 return ret;
 107
 108         c = new_commit(state);
 109
 110         /*
 111          * Figure out what fence to wait for:
 112          */
 113         for (i = 0; i < nplanes; i++) {
 114                 struct drm_plane *plane = state->planes[i];
 115                 struct drm_plane_state *new_state = state->plane_states[i];
 116
 117                 if (!plane)
 118                         continue;
 119
 120                 if ((plane->state->fb != new_state->fb) && new_state->fb)
 121                         add_fb(c, new_state->fb);
 122         }
 123
 124         /*
 125          * This is the point of no return - everything below never fails except
 126          * when the hw goes bonghits. Which means we can commit the new state on
 127          * the software side now.
 128          */
 129
 130         drm_atomic_helper_swap_state(dev, state);
 131
 132         /*
 133          * Everything below can be run asynchronously without the need to grab
 134          * any modeset locks at all under one conditions: It must be guaranteed
 135          * that the asynchronous work has either been cancelled (if the driver
 136          * supports it, which at least requires that the framebuffers get
 137          * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
 138          * before the new state gets committed on the software side with
 139          * drm_atomic_helper_swap_state().
 140          *
 141          * This scheme allows new atomic state updates to be prepared and
 142          * checked in parallel to the asynchronous completion of the previous
 143          * update. Which is important since compositors need to figure out the
 144          * composition of the next frame right after having submitted the
 145          * current layout.
 146          */
 147
 148         if (async) {
 149                 msm_queue_fence_cb(dev, &c->fence_cb, c->fence);
 150                 return 0;
 151         }
 152
 153         ret = msm_wait_fence_interruptable(dev, c->fence, NULL);
 154         if (ret) {
 155                 WARN_ON(ret);  // TODO unswap state back?  or??
 156                 kfree(c);
 157                 return ret;
 158         }
 159
 160         complete_commit(c);
 161
 162         return 0;
 163 }