[ 01/68] drm/i915: mask transcoder select bits before setting them on LVDS

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

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

From: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>

commit 7885d2052bd94395e337709cfba093a41f273ff1 upstream.

The transcoder port may changed from mode set to mode set, so make sure
to mask out the selection bits before setting the right ones or we'll
get black screens when going from transcoder B to A.

Tested-by: Vincent Vanackere <vincent.vanackere@xxxxxxxxx>
Signed-off-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Reviewed-by: Keith Packard <keithp@xxxxxxxxxx>
Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>
Cc: Jonathan Nieder <jrnieder@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
 drivers/gpu/drm/i915/intel_display.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5646,12 +5646,15 @@ static int ironlake_crtc_mode_set(struct
 	if (is_lvds) {
 		temp = I915_READ(PCH_LVDS);
 		temp |= LVDS_PORT_EN | LVDS_A0A2_CLKA_POWER_UP;
-		if (HAS_PCH_CPT(dev))
+		if (HAS_PCH_CPT(dev)) {
+			temp &= ~PORT_TRANS_SEL_MASK;
 			temp |= PORT_TRANS_SEL_CPT(pipe);
-		else if (pipe == 1)
-			temp |= LVDS_PIPEB_SELECT;
-		else
-			temp &= ~LVDS_PIPEB_SELECT;
+		} else {
+			if (pipe == 1)
+				temp |= LVDS_PIPEB_SELECT;
+			else
+				temp &= ~LVDS_PIPEB_SELECT;
+		}
 
 		/* set the corresponsding LVDS_BORDER bit */
 		temp |= dev_priv->lvds_border_bits;


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