target/linux/brcm2708/patches-4.4/0460-drm-vc4-Return-EBUSY-if-there-s-already-a-pending-fl.patch

   1 From 52367e61f8707fe5e22aabf3c769e27f11aa3300 Mon Sep 17 00:00:00 2001
   2 From: Robert Foss <robert.foss@collabora.com>
   3 Date: Tue, 3 May 2016 13:48:20 -0400
   4 Subject: [PATCH] drm/vc4: Return -EBUSY if there's already a pending flip
   5  event.
   6
   7 As per the documentation in drm_crtc.h, atomic_commit should return
   8 -EBUSY if an asynchronous update is requested and there is an earlier
   9 update pending.
  10
  11 v2: Rebase on the s/async/nonblock/ change.
  12
  13 Signed-off-by: Robert Foss <robert.foss@collabora.com>
  14 Reviewed-by: Eric Anholt <eric@anholt.net>
  15 (cherry picked from commit e7c31f6f25b84fed961dc0dce6248878527693ae)
  16 ---
  17  drivers/gpu/drm/vc4/vc4_kms.c | 16 ++++++++++++----
  18  1 file changed, 12 insertions(+), 4 deletions(-)
  19
  20 --- a/drivers/gpu/drm/vc4/vc4_kms.c
  21 +++ b/drivers/gpu/drm/vc4/vc4_kms.c
  22 @@ -119,10 +119,18 @@ static int vc4_atomic_commit(struct drm_
  23                 return -ENOMEM;
  24
  25         /* Make sure that any outstanding modesets have finished. */
  26 -       ret = down_interruptible(&vc4->async_modeset);
  27 -       if (ret) {
  28 -               kfree(c);
  29 -               return ret;
  30 +       if (nonblock) {
  31 +               ret = down_trylock(&vc4->async_modeset);
  32 +               if (ret) {
  33 +                       kfree(c);
  34 +                       return -EBUSY;
  35 +               }
  36 +       } else {
  37 +               ret = down_interruptible(&vc4->async_modeset);
  38 +               if (ret) {
  39 +                       kfree(c);
  40 +                       return ret;
  41 +               }
  42         }
  43
  44         ret = drm_atomic_helper_prepare_planes(dev, state);