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>

drivers/gpu/drm/i915/i915_reg.h

@@ -3189,6 +3189,7 @@
 #define  FDI_LINK_TRAIN_NONE_IVB            (3<<8)
 
 /* both Tx and Rx */
+#define  FDI_COMPOSITE_SYNC		(1<<11)
 #define  FDI_LINK_TRAIN_AUTO		(1<<10)
 #define  FDI_SCRAMBLING_ENABLE          (0<<7)
 #define  FDI_SCRAMBLING_DISABLE         (1<<7)

drivers/gpu/drm/i915/intel_display.c

@@ -2601,6 +2601,7 @@ static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
 	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 @@ static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
 	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);