drm/i915: Do not clobber the contents of TRANS_DP_CTL when enabling.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1490a8c..c7f19ec 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2097,9 +2097,10 @@
int reg;
reg = I915_READ(trans_dp_ctl);
- reg &= ~TRANS_DP_PORT_SEL_MASK;
- reg = TRANS_DP_OUTPUT_ENABLE |
- TRANS_DP_ENH_FRAMING;
+ reg &= ~(TRANS_DP_PORT_SEL_MASK |
+ TRANS_DP_SYNC_MASK);
+ reg |= (TRANS_DP_OUTPUT_ENABLE |
+ TRANS_DP_ENH_FRAMING);
if (crtc->mode.flags & DRM_MODE_FLAG_PHSYNC)
reg |= TRANS_DP_HSYNC_ACTIVE_HIGH;