drm/i915: set CPT FDI RX polarity bits based on VBT

Check the VBT to see if the machine has inverted FDI RX polarity on
CPT. Based on this bit, set the appropriate bit on the TRANS_CHICKEN2
registers.

This should fix some machines that were showing black screens on all
outputs.

Cc: [e-mail]
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=60029
Signed-off-by: Paulo Zanoni <[e-mail]>
Reviewed-by: Imre Deak <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/i915/i915_drv.h

···
 	unsigned int int_crt_support:1;
 	unsigned int lvds_use_ssc:1;
 	unsigned int display_clock_mode:1;
+	unsigned int fdi_rx_polarity_inverted:1;
 	int lvds_ssc_freq;
 	unsigned int bios_lvds_val; /* initial [PCH_]LVDS reg val in VBIOS */
 	struct {

drivers/gpu/drm/i915/i915_reg.h

···
 #define _TRANSB_CHICKEN2	 0xf1064
 #define TRANS_CHICKEN2(pipe) _PIPE(pipe, _TRANSA_CHICKEN2, _TRANSB_CHICKEN2)
 #define  TRANS_CHICKEN2_TIMING_OVERRIDE		(1<<31)
-
+#define  TRANS_CHICKEN2_FDI_POLARITY_REVERSED	(1<<29)
 
 #define SOUTH_CHICKEN1		0xc2000
 #define  FDIA_PHASE_SYNC_SHIFT_OVR	19

drivers/gpu/drm/i915/intel_bios.c

···
 		dev_priv->lvds_ssc_freq =
 			intel_bios_ssc_frequency(dev, general->ssc_freq);
 		dev_priv->display_clock_mode = general->display_clock_mode;
-		DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d display_clock_mode %d\n",
+		dev_priv->fdi_rx_polarity_inverted = general->fdi_rx_polarity_inverted;
+		DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d display_clock_mode %d fdi_rx_polarity_inverted %d\n",
 			      dev_priv->int_tv_support,
 			      dev_priv->int_crt_support,
 			      dev_priv->lvds_use_ssc,
 			      dev_priv->lvds_ssc_freq,
-			      dev_priv->display_clock_mode);
+			      dev_priv->display_clock_mode,
+			      dev_priv->fdi_rx_polarity_inverted);
 	}
 }
 

drivers/gpu/drm/i915/intel_bios.h

···
         /* bits 3 */
 	u8 disable_smooth_vision:1;
 	u8 single_dvi:1;
-	u8 rsvd9:6; /* finish byte */
+	u8 rsvd9:1;
+	u8 fdi_rx_polarity_inverted:1;
+	u8 rsvd10:4; /* finish byte */
 
         /* bits 4 */
 	u8 legacy_monitor_detect;

drivers/gpu/drm/i915/intel_pm.c

···
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int pipe;
+	uint32_t val;
 
 	/*
 	 * On Ibex Peak and Cougar Point, we need to disable clock
···
 	/* The below fixes the weird display corruption, a few pixels shifted
 	 * downward, on (only) LVDS of some HP laptops with IVY.
 	 */
-	for_each_pipe(pipe)
-		I915_WRITE(TRANS_CHICKEN2(pipe), TRANS_CHICKEN2_TIMING_OVERRIDE);
+	for_each_pipe(pipe) {
+		val = TRANS_CHICKEN2_TIMING_OVERRIDE;
+		if (dev_priv->fdi_rx_polarity_inverted)
+			val |= TRANS_CHICKEN2_FDI_POLARITY_REVERSED;
+		I915_WRITE(TRANS_CHICKEN2(pipe), val);
+	}
 	/* WADP0ClockGatingDisable */
 	for_each_pipe(pipe) {
 		I915_WRITE(TRANS_CHICKEN1(pipe),