drm/i915: Add limited color range readout for HDMI/DP ports on g4x/vlv/chv

The limited color range knob is in the port registers on
g4x and vlv/chv for HDMI, and on g4x for DP. Add the relevant code
to read out the hardware state into pipe config. On vlv/chv the
DP port limited color range knob is in PIPECONF for which we
already have readout code.

Cc: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -1631,6 +1631,10 @@ static void intel_dp_get_config(struct intel_encoder *encoder,
 
 	pipe_config->adjusted_mode.flags |= flags;
 
+	if (!HAS_PCH_SPLIT(dev) && !IS_VALLEYVIEW(dev) &&
+	    tmp & DP_COLOR_RANGE_16_235)
+		pipe_config->limited_color_range = true;
+
 	pipe_config->has_dp_encoder = true;
 
 	intel_dp_get_m_n(crtc, pipe_config);

drivers/gpu/drm/i915/intel_hdmi.c

@@ -712,7 +712,8 @@ static void intel_hdmi_get_config(struct intel_encoder *encoder,
 				  struct intel_crtc_config *pipe_config)
 {
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
-	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	struct drm_device *dev = encoder->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 tmp, flags = 0;
 	int dotclock;
 
@@ -734,6 +735,10 @@ static void intel_hdmi_get_config(struct intel_encoder *encoder,
 	if (tmp & HDMI_MODE_SELECT_HDMI)
 		pipe_config->has_audio = true;
 
+	if (!HAS_PCH_SPLIT(dev) &&
+	    tmp & HDMI_COLOR_RANGE_16_235)
+		pipe_config->limited_color_range = true;
+
 	pipe_config->adjusted_mode.flags |= flags;
 
 	if ((tmp & SDVO_COLOR_FORMAT_MASK) == HDMI_COLOR_FORMAT_12bpc)