drm/i915: state readout and cross checking for limited_color_range

At least on those platforms which have a simple bit and don't rely
on the fully programmable CSC unit to do this.

Note that with the current code this includes CHV, but I guess that
platform will match BYT.
Reviewed-by: Naresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -6062,6 +6062,9 @@ static bool i9xx_get_pipe_config(struct intel_crtc *crtc,
 		}
 	}
 
+	if (IS_VALLEYVIEW(dev) && (tmp & PIPECONF_COLOR_RANGE_SELECT))
+		pipe_config->limited_color_range = true;
+
 	if (INTEL_INFO(dev)->gen < 4)
 		pipe_config->double_wide = tmp & PIPECONF_DOUBLE_WIDE;
 
@@ -7068,6 +7071,9 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
 		break;
 	}
 
+	if (tmp & PIPECONF_COLOR_RANGE_SELECT)
+		pipe_config->limited_color_range = true;
+
 	if (I915_READ(PCH_TRANSCONF(crtc->pipe)) & TRANS_ENABLE) {
 		struct intel_shared_dpll *pll;
 
@@ -9884,6 +9890,9 @@ intel_pipe_config_compare(struct drm_device *dev,
 
 	PIPE_CONF_CHECK_I(pixel_multiplier);
 	PIPE_CONF_CHECK_I(has_hdmi_sink);
+	if ((INTEL_INFO(dev)->gen < 8 && !IS_HASWELL(dev)) ||
+	    IS_VALLEYVIEW(dev))
+		PIPE_CONF_CHECK_I(limited_color_range);
 
 	PIPE_CONF_CHECK_FLAGS(adjusted_mode.flags,
 			      DRM_MODE_FLAG_INTERLACE);

drivers/gpu/drm/i915/intel_sdvo.c

@@ -1348,6 +1348,8 @@ static void intel_sdvo_get_config(struct intel_encoder *encoder,
 	u8 val;
 	bool ret;
 
+	sdvox = I915_READ(intel_sdvo->sdvo_reg);
+
 	ret = intel_sdvo_get_input_timing(intel_sdvo, &dtd);
 	if (!ret) {
 		/* Some sdvo encoders are not spec compliant and don't
@@ -1376,7 +1378,6 @@ static void intel_sdvo_get_config(struct intel_encoder *encoder,
 	 * other platfroms.
 	 */
 	if (IS_I915G(dev) || IS_I915GM(dev)) {
-		sdvox = I915_READ(intel_sdvo->sdvo_reg);
 		pipe_config->pixel_multiplier =
 			((sdvox & SDVO_PORT_MULTIPLY_MASK)
 			 >> SDVO_PORT_MULTIPLY_SHIFT) + 1;
@@ -1405,6 +1406,9 @@ static void intel_sdvo_get_config(struct intel_encoder *encoder,
 		}
 	}
 
+	if (sdvox & HDMI_COLOR_RANGE_16_235)
+		pipe_config->limited_color_range = true;
+
 	WARN(encoder_pixel_multiplier != pipe_config->pixel_multiplier,
 	     "SDVO pixel multiplier mismatch, port: %i, encoder: %i\n",
 	     pipe_config->pixel_multiplier, encoder_pixel_multiplier);