[PATCH/RFC 05/12] drm: rcar-du: lvds: Add data swap support

[Fabrizio Castro <fabrizio.castro@bp.renesas.com>]

When in vertical stripe mode of operation, there is the option
of swapping even data and odd data on the two LVDS interfaces
used to drive the video output.
Add data swap support by exposing a new DT property named
"renesas,swap-data".

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
---
 drivers/gpu/drm/rcar-du/rcar_lvds.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
index 3aeaf9e..c306fab 100644
--- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
+++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
@@ -69,6 +69,7 @@ struct rcar_lvds {
 
 	struct drm_bridge *companion;
 	bool dual_link;
+	bool stripe_swap_data;
 };
 
 #define bridge_to_rcar_lvds(bridge) \
@@ -439,12 +440,16 @@ static void rcar_lvds_enable(struct drm_bridge *bridge)
 	rcar_lvds_write(lvds, LVDCHCR, lvdhcr);
 
 	if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK) {
-		/*
-		 * Configure vertical stripe based on the mode of operation of
-		 * the connected device.
-		 */
-		rcar_lvds_write(lvds, LVDSTRIPE,
-				lvds->dual_link ? LVDSTRIPE_ST_ON : 0);
+		u32 lvdstripe = 0;
+
+		if (lvds->dual_link)
+			/*
+			 * Configure vertical stripe based on the mode of
+			 * operation of the connected device.
+			 */
+			lvdstripe = LVDSTRIPE_ST_ON | (lvds->stripe_swap_data ?
+						       LVDSTRIPE_ST_SWAP : 0);
+		rcar_lvds_write(lvds, LVDSTRIPE, lvdstripe);
 	}
 
 	/*
@@ -770,8 +775,12 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
 		}
 	}
 
-	if (lvds->dual_link)
+	if (lvds->dual_link) {
+		lvds->stripe_swap_data = of_property_read_bool(
+						lvds->dev->of_node,
+						"renesas,swap-data");
 		ret = rcar_lvds_parse_dt_companion(lvds);
+	}
 
 done:
 	of_node_put(local_output);
-- 
2.7.4