This is a note to let you know that I've just added the patch titled
drm/msm/a5xx: fix the emptyness check in the preempt code
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-msm-a5xx-fix-the-emptyness-check-in-the-preempt-.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f9f4ec3b6b55bad80f950d8965fcfa800c5807f0
Author: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Date: Tue Feb 14 05:09:55 2023 +0300
drm/msm/a5xx: fix the emptyness check in the preempt code
[ Upstream commit b4fb748f0b734ce1d2e7834998cc599fcbd25d67 ]
Quoting Yassine: ring->memptrs->rptr is never updated and stays 0, so
the comparison always evaluates to false and get_next_ring always
returns ring 0 thinking it isn't empty.
Fix this by calling get_rptr() instead of reading rptr directly.
Reported-by: Yassine Oudjana <y.oudjana@xxxxxxxxxxxxxx>
Fixes: b1fc2839d2f9 ("drm/msm: Implement preemption for A5XX targets")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Patchwork: https://patchwork.freedesktop.org/patch/522642/
Link: https://lore.kernel.org/r/20230214020956.164473-4-dmitry.baryshkov@xxxxxxxxxx
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
index 8abc9a2b114a2..6e326d851ba53 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
@@ -63,7 +63,7 @@ static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
struct msm_ringbuffer *ring = gpu->rb[i];
spin_lock_irqsave(&ring->preempt_lock, flags);
- empty = (get_wptr(ring) == ring->memptrs->rptr);
+ empty = (get_wptr(ring) == gpu->funcs->get_rptr(gpu, ring));
spin_unlock_irqrestore(&ring->preempt_lock, flags);
if (!empty)
