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/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 281db6e..97a35a4 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2928,6 +2928,7 @@
 #define  TRANS_DP_VSYNC_ACTIVE_LOW     0
 #define  TRANS_DP_HSYNC_ACTIVE_HIGH    (1<<3)
 #define  TRANS_DP_HSYNC_ACTIVE_LOW     0
+#define  TRANS_DP_SYNC_MASK    (3<<3)
 
 /* SNB eDP training params */
 /* SNB A-stepping */

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1490a8c..c7f19ec 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2097,9 +2097,10 @@ static void ironlake_crtc_dpms(struct drm_crtc *crtc, int mode)
                                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;