[PATCH 3/7] drm/i915: set bpc for DP transcoder

[Jesse Barnes <jbarnes@virtuousgeek.org>]

This may not be the default value, so pull the bpc out of the pipe reg
and write it to the DP transcoder so proper dithering and signaling
occurs.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_display.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 69649b2..8ef0c39 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2504,6 +2504,7 @@ static void ironlake_pch_enable(struct drm_crtc *crtc)
 	/* For PCH DP, enable TRANS_DP_CTL */
 	if (HAS_PCH_CPT(dev) &&
 	    intel_pipe_has_type(crtc, INTEL_OUTPUT_DISPLAYPORT)) {
+		u32 bpc = (I915_READ(PIPECONF(pipe)) & PIPE_BPC_MASK) >> 5;
 		reg = TRANS_DP_CTL(pipe);
 		temp = I915_READ(reg);
 		temp &= ~(TRANS_DP_PORT_SEL_MASK |
@@ -2511,7 +2512,7 @@ static void ironlake_pch_enable(struct drm_crtc *crtc)
 			  TRANS_DP_BPC_MASK);
 		temp |= (TRANS_DP_OUTPUT_ENABLE |
 			 TRANS_DP_ENH_FRAMING);
-		temp |= TRANS_DP_8BPC;
+		temp |= bpc << 9; /* same format but at 11:9 */
 
 		if (crtc->mode.flags & DRM_MODE_FLAG_PHSYNC)
 			temp |= TRANS_DP_HSYNC_ACTIVE_HIGH;
-- 
1.7.4.1