[PATCH 3.16 008/366] drm: rcar-du: lvds: Fix LVDS startup on R-Car Gen2

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>

commit 8525d04ba8a6a9ecfa4bd619c988ca873a5fc2a4 upstream.

According to the latest revision 2.00 of the R-Car Gen2 manual, the LVDS
and the bias circuit must be enabled after the LVDS I/O pins are
enabled, not before. Fix the Gen2 LVDS startup sequence accordingly.

While at it, also fix the comment preceding the first LVDCR0 write that
still talks about hardcoding the LVDS mode 0.

Fixes: 90374b5c25c9 ("drm/rcar-du: Add internal LVDS encoder support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Tested-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Mode is always 0
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_lvdsenc.c
@@ -87,10 +87,8 @@ static int rcar_du_lvdsenc_start(struct
 
 	rcar_lvds_write(lvds, LVDCHCR, lvdhcr);
 
-	/* Select the input, hardcode mode 0, enable LVDS operation and turn
-	 * bias circuitry on.
-	 */
-	lvdcr0 = LVDCR0_BEN | LVDCR0_LVEN;
+	/* Select the input and set the LVDS mode. */
+	lvdcr0 = 0;
 	if (rcrtc->index == 2)
 		lvdcr0 |= LVDCR0_DUSEL;
 	rcar_lvds_write(lvds, LVDCR0, lvdcr0);
@@ -99,6 +97,10 @@ static int rcar_du_lvdsenc_start(struct
 	rcar_lvds_write(lvds, LVDCR1, LVDCR1_CHSTBY(3) | LVDCR1_CHSTBY(2) |
 			LVDCR1_CHSTBY(1) | LVDCR1_CHSTBY(0) | LVDCR1_CLKSTBY);
 
+	/* Enable LVDS operation and turn bias circuitry on. */
+	lvdcr0 |= LVDCR0_BEN | LVDCR0_LVEN;
+	rcar_lvds_write(lvds, LVDCR0, lvdcr0);
+
 	/* Turn the PLL on, wait for the startup delay, and turn the output
 	 * on.
 	 */