drm/mediatek: Check if fb is null

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@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index 266c5c5..1c295c5 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -291,7 +291,7 @@ void mtk_ovl_layer_config(struct device *dev, 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) {