drm/i915: always set FDI composite sync bit

It's needed for 3 pipe support as well as just regular functionality
(e.g. DisplayPort).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Adam Jackson <ajax@redhat.com>
Tested-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 186cde2..2e28c68 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2601,6 +2601,7 @@
 	temp |= FDI_LINK_TRAIN_PATTERN_1_IVB;
 	temp &= ~FDI_LINK_TRAIN_VOL_EMP_MASK;
 	temp |= FDI_LINK_TRAIN_400MV_0DB_SNB_B;
+	temp |= FDI_COMPOSITE_SYNC;
 	I915_WRITE(reg, temp | FDI_TX_ENABLE);
 
 	reg = FDI_RX_CTL(pipe);
@@ -2608,6 +2609,7 @@
 	temp &= ~FDI_LINK_TRAIN_AUTO;
 	temp &= ~FDI_LINK_TRAIN_PATTERN_MASK_CPT;
 	temp |= FDI_LINK_TRAIN_PATTERN_1_CPT;
+	temp |= FDI_COMPOSITE_SYNC;
 	I915_WRITE(reg, temp | FDI_RX_ENABLE);
 
 	POSTING_READ(reg);