[PATCH v3 3/5] drm/msm: fix fb references in async update

From: Helen Koike <helen.koike@collabora.com>
To: dri-devel@lists.freedesktop.org, nicholas.kazlauskas@amd.com
Cc: andrey.grodzovsky@amd.com, daniel.vetter@ffwll.ch,
	linux-kernel@vger.kernel.org, "Tomasz Figa" <tfiga@chromium.org>,
	boris.brezillon@collabora.com, "David Airlie" <airlied@linux.ie>,
	"Sean Paul" <seanpaul@google.com>,
	kernel@collabora.com, harry.wentland@amd.com,
	"Stéphane Marchesin" <marcheu@google.com>,
	"Helen Koike" <helen.koike@collabora.com>,
	stable@vger.kernel.org, "Sean Paul" <sean@poorly.run>,
	linux-arm-msm@vger.kernel.org, robdclark@gmail.com,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	freedreno@lists.freedesktop.org,
	"Mamta Shukla" <mamtashukla555@gmail.com>,
	"Daniel Vetter" <daniel@ffwll.ch>
Subject: [PATCH v3 3/5] drm/msm: fix fb references in async update
Date: Wed, 13 Mar 2019 21:20:24 -0300	[thread overview]
Message-ID: <20190314002027.7833-4-helen.koike@collabora.com> (raw)
In-Reply-To: <20190314002027.7833-1-helen.koike@collabora.com>

Async update callbacks are expected to set the old_fb in the new_state
so prepare/cleanup framebuffers are balanced.

Cc: <stable@vger.kernel.org> # v4.14+
Fixes: 224a4c970987 ("drm/msm: update cursors asynchronously through atomic")
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>

---
Hello,

As mentioned in the cover letter,
But I couldn't test on MSM because I don't have the hardware and I would
appreciate if anyone could test it.

In other platforms (VC4, AMD, Rockchip), there is a hidden
drm_framebuffer_get(new_fb)/drm_framebuffer_put(old_fb) in async_update
that is wrong, but I couldn't identify those here, not sure if it is hidden
somewhere else, but if tests fail this is probably the cause.

Thanks!
Helen

Changes in v3: None
Changes in v2:
- update CC stable and Fixes tag

 drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
index be13140967b4..b854f471e9e5 100644
--- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
+++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
@@ -502,6 +502,8 @@ static int mdp5_plane_atomic_async_check(struct drm_plane *plane,
 static void mdp5_plane_atomic_async_update(struct drm_plane *plane,
 					   struct drm_plane_state *new_state)
 {
+	struct drm_framebuffer *old_fb = plane->state->fb;
+
 	plane->state->src_x = new_state->src_x;
 	plane->state->src_y = new_state->src_y;
 	plane->state->crtc_x = new_state->crtc_x;
@@ -524,6 +526,8 @@ static void mdp5_plane_atomic_async_update(struct drm_plane *plane,
 
 	*to_mdp5_plane_state(plane->state) =
 		*to_mdp5_plane_state(new_state);
+
+	new_state->fb = old_fb;
 }
 
 static const struct drm_plane_helper_funcs mdp5_plane_helper_funcs = {
-- 
2.20.1

