This is a note to let you know that I've just added the patch titled
drm/msm: Fix dirtyfb refcounting
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-fix-dirtyfb-refcounting.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.
>From 9225b337072a10bf9b09df8bf281437488dd8a26 Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@xxxxxxxxxxxx>
Date: Fri, 4 Mar 2022 12:21:45 -0800
Subject: drm/msm: Fix dirtyfb refcounting
From: Rob Clark <robdclark@xxxxxxxxxxxx>
commit 9225b337072a10bf9b09df8bf281437488dd8a26 upstream.
refcount_t complains about 0->1 transitions, which isn't *quite* what we
wanted. So use dirtyfb==1 to mean that the fb is not connected to any
output that requires dirtyfb flushing, so that we can keep the underflow
and overflow checking.
Fixes: 9e4dde28e9cd ("drm/msm: Avoid dirtyfb stalls on video mode displays (v2)")
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220304202146.845566-1-robdclark@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/msm/msm_fb.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/msm/msm_fb.c
+++ b/drivers/gpu/drm/msm/msm_fb.c
@@ -37,7 +37,7 @@ static int msm_framebuffer_dirtyfb(struc
/* If this fb is not used on any display requiring pixel data to be
* flushed, then skip dirtyfb
*/
- if (refcount_read(&msm_fb->dirtyfb) == 0)
+ if (refcount_read(&msm_fb->dirtyfb) == 1)
return 0;
return drm_atomic_helper_dirtyfb(fb, file_priv, flags, color,
@@ -221,6 +221,8 @@ static struct drm_framebuffer *msm_frame
goto fail;
}
+ refcount_set(&msm_fb->dirtyfb, 1);
+
drm_dbg_state(dev, "create: FB ID: %d (%p)", fb->base.id, fb);
return fb;
Patches currently in stable-queue which might be from robdclark@xxxxxxxxxxxx are
queue-5.15/drm-msm-avoid-dirtyfb-stalls-on-video-mode-displays-.patch
queue-5.15/drm-msm-fix-dirtyfb-refcounting.patch
queue-5.15/drm-msm-mdp5-fix-global-state-lock-backoff.patch
queue-5.15/drm-msm-dpu-fix-for-non-visible-planes.patch
