[PATCH v2 4/5] drm/vc4: 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, eric@anholt.net,
	"Daniel Vetter" <daniel@ffwll.ch>
Subject: [PATCH v2 4/5] drm/vc4: fix fb references in async update
Date: Mon, 11 Mar 2019 23:22:02 -0300	[thread overview]
Message-ID: <20190312022204.2775-5-helen.koike@collabora.com> (raw)
In-Reply-To: <20190312022204.2775-1-helen.koike@collabora.com>

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

Calling drm_atomic_set_fb_for_plane() (which gets a reference of the new
fb and put the old fb) is not required, as it's taken care by
drm_mode_cursor_universal() when calling drm_atomic_helper_update_plane().

Cc: <stable@vger.kernel.org> # v4.19+
Fixes: 539c320bfa97 ("drm/vc4: update cursors asynchronously through atomic")
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

---
Hello,

I tested on a Raspberry Pi model B rev2 with igt plane_cursor_legacy and
kms_cursor_legacy and I didn't see any regressions.

Changes in v2:
- Added reviewed-by tag
- updated CC stable and Fixes tag

 drivers/gpu/drm/vc4/vc4_plane.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index 1babfeca0c92..1235e53b22a3 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -968,7 +968,7 @@ static void vc4_plane_atomic_async_update(struct drm_plane *plane,
 {
 	struct vc4_plane_state *vc4_state, *new_vc4_state;
 
-	drm_atomic_set_fb_for_plane(plane->state, state->fb);
+	swap(plane->state->fb, state->fb);
 	plane->state->crtc_x = state->crtc_x;
 	plane->state->crtc_y = state->crtc_y;
 	plane->state->crtc_w = state->crtc_w;
-- 
2.20.1

