[PATCH 5.11 258/775] drm/mediatek: Check if fb is null

[Greg Kroah-Hartman]

From: Yongqiang Niu <yongqiang.niu@xxxxxxxxxxxx>

[ Upstream commit b1d685b6467ac0d98fc63989f71b4ca9186be5d4 ]

It's possible that state->base.fb is null. Add a check before access its
format.

Fixes: b6b1bb980ec4 ("drm/mediatek: Turn off Alpha bit when plane format has no alpha")
Signed-off-by: Yongqiang Niu <yongqiang.niu@xxxxxxxxxxxx>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index 74ef6fc0528b6..523716e3c278a 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -267,7 +267,7 @@ static void mtk_ovl_layer_config(struct mtk_ddp_comp *comp, unsigned int idx,
 	}
 
 	con = ovl_fmt_convert(ovl, fmt);
-	if (state->base.fb->format->has_alpha)
+	if (state->base.fb && state->base.fb->format->has_alpha)
 		con |= OVL_CON_AEN | OVL_CON_ALPHA;
 
 	if (pending->rotation & DRM_MODE_REFLECT_Y) {
-- 
2.27.0