drm/i915: program FDI_RX TP and FDI delays

This is required for a stable FDI connection.

v2: fix and simplify the FDI_RX_MISC bits as noticed by Paulo Zanoni.

CC: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NEugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -3854,6 +3854,9 @@
 #define _FDI_RXA_TUSIZE2         0xf0038
 #define _FDI_RXB_TUSIZE1         0xf1030
 #define _FDI_RXB_TUSIZE2         0xf1038
+#define  FDI_RX_TP1_TO_TP2_48	(2<<20)
+#define  FDI_RX_TP1_TO_TP2_64	(3<<20)
+#define  FDI_RX_FDI_DELAY_90	(0x90<<0)
 #define FDI_RX_MISC(pipe) _PIPE(pipe, _FDI_RXA_MISC, _FDI_RXB_MISC)
 #define FDI_RX_TUSIZE1(pipe) _PIPE(pipe, _FDI_RXA_TUSIZE1, _FDI_RXB_TUSIZE1)
 #define FDI_RX_TUSIZE2(pipe) _PIPE(pipe, _FDI_RXA_TUSIZE2, _FDI_RXB_TUSIZE2)

drivers/gpu/drm/i915/intel_ddi.c

@@ -170,6 +170,15 @@ void hsw_fdi_link_train(struct drm_crtc *crtc)
 
 		udelay(600);
 
+		/* We need to program FDI_RX_MISC with the default TP1 to TP2
+		 * values before enabling the receiver, and configure the delay
+		 * for the FDI timing generator to 90h. Luckily, all the other
+		 * bits are supposed to be zeroed, so we can write those values
+		 * directly.
+		 */
+		I915_WRITE(FDI_RX_MISC(pipe), FDI_RX_TP1_TO_TP2_48 |
+				FDI_RX_FDI_DELAY_90);
+
 		/* Enable CPU FDI Receiver with auto-training */
 		reg = FDI_RX_CTL(pipe);
 		I915_WRITE(reg,