drm/mediatek: Turn off Alpha bit when plane format has no alpha

This change enables XR24 format to be displayed as an overlay on top of
the primary plane.

Suggested-by: Sean Paul <[email protected]>
To: CK Hu <[email protected]>
To: [email protected]
Cc: Daniele Castagna <[email protected]>
Cc: Philipp Zabel <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Mark Yacoub <[email protected]>
Signed-off-by: CK Hu <[email protected]>

Author: Mark Yacoub

drivers/gpu/drm/mediatek/mtk_disp_ovl.c

@@ -266,7 +266,7 @@ static void mtk_ovl_layer_config(struct mtk_ddp_comp *comp, unsigned int idx,
 	}
 
 	con = ovl_fmt_convert(ovl, fmt);
-	if (idx != 0)
+	if (state->base.fb->format->has_alpha)
 		con |= OVL_CON_AEN | OVL_CON_ALPHA;
 
 	if (pending->rotation & DRM_MODE_REFLECT_Y) {