From: Maxime Ripard <maxime.ripard@bootlin.com>
Date: Thu, 17 May 2018 15:37:59 +0200
Subject: drm/vc4: plane: Expand the lower bits by repeating the higher bits
Git-commit: 3257ec797d3a8c5232389eb1952d4451e80f3931
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

The vc4 HVS uses an internal RGB888 representation of the frames, and will
by default expand formats using a lower depth using zeros.

This causes an issue when we try to use other compositing software such as
pixman that fill the missing bits by repeating the higher significant bits.
As such, we can't check the display output in a reliable way by doing a
software composition and an hardware one and compare both.

To prevent this, force the same behaviour so that we can do such things.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180517133759.25626-1-maxime.ripard@bootlin.com

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/vc4/vc4_plane.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -547,6 +547,7 @@ static int vc4_plane_mode_set(struct drm
 	/* Control word */
 	vc4_dlist_write(vc4_state,
 			SCALER_CTL0_VALID |
+			VC4_SET_FIELD(SCALER_CTL0_RGBA_EXPAND_ROUND, SCALER_CTL0_RGBA_EXPAND) |
 			(format->pixel_order << SCALER_CTL0_ORDER_SHIFT) |
 			(format->hvs << SCALER_CTL0_PIXEL_FORMAT_SHIFT) |
 			VC4_SET_FIELD(tiling, SCALER_CTL0_TILING) |