drm/i915: Add support for limited color range of broadcast outputs

In order to prevent "crushed blacks" on TVs, the range of the RGB output
may be limited to 16-235. This used to be available through Xorg under
the "Broadcast RGB" option, so reintroduce support for KMS.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34543
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.h

@@ -707,6 +707,8 @@ typedef struct drm_i915_private {
 
 	/* list of fbdev register on this device */
 	struct intel_fbdev *fbdev;
+
+	struct drm_property *broadcast_rgb_property;
 } drm_i915_private_t;
 
 struct drm_i915_gem_object {

drivers/gpu/drm/i915/i915_reg.h

@@ -1387,6 +1387,7 @@
 #define   SDVO_ENCODING_HDMI		(0x2 << 10)
 /** Requird for HDMI operation */
 #define   SDVO_NULL_PACKETS_DURING_VSYNC (1 << 9)
+#define   SDVO_COLOR_RANGE_16_235	(1 << 8)
 #define   SDVO_BORDER_ENABLE		(1 << 7)
 #define   SDVO_AUDIO_ENABLE		(1 << 6)
 /** New with 965, default is to be set */

drivers/gpu/drm/i915/intel_dp.c

@@ -49,6 +49,7 @@ struct intel_dp {
 	uint8_t  link_configuration[DP_LINK_CONFIGURATION_SIZE];
 	bool has_audio;
 	int force_audio;
+	uint32_t color_range;
 	int dpms_mode;
 	uint8_t link_bw;
 	uint8_t lane_count;
@@ -741,8 +742,8 @@ intel_dp_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode,
 	struct drm_crtc *crtc = intel_dp->base.base.crtc;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 
-	intel_dp->DP = (DP_VOLTAGE_0_4 |
-		       DP_PRE_EMPHASIS_0);
+	intel_dp->DP = DP_VOLTAGE_0_4 | DP_PRE_EMPHASIS_0;
+	intel_dp->DP |= intel_dp->color_range;
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
 		intel_dp->DP |= DP_SYNC_HS_HIGH;
@@ -1680,6 +1681,7 @@ intel_dp_set_property(struct drm_connector *connector,
 		      struct drm_property *property,
 		      uint64_t val)
 {
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	int ret;
 
@@ -1708,6 +1710,14 @@ intel_dp_set_property(struct drm_connector *connector,
 		goto done;
 	}
 
+	if (property == dev_priv->broadcast_rgb_property) {
+		if (val == !!intel_dp->color_range)
+			return 0;
+
+		intel_dp->color_range = val ? DP_COLOR_RANGE_16_235 : 0;
+		goto done;
+	}
+
 	return -EINVAL;
 
 done:
@@ -1827,6 +1837,8 @@ intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connect
 		intel_dp->force_audio_property->values[1] = 1;
 		drm_connector_attach_property(connector, intel_dp->force_audio_property, 0);
 	}
+
+	intel_attach_broadcast_rgb_property(connector);
 }
 
 void

drivers/gpu/drm/i915/intel_drv.h

@@ -237,6 +237,8 @@ struct intel_unpin_work {
 int intel_ddc_get_modes(struct drm_connector *c, struct i2c_adapter *adapter);
 extern bool intel_ddc_probe(struct intel_encoder *intel_encoder, int ddc_bus);
 
+extern void intel_attach_broadcast_rgb_property(struct drm_connector *connector);
+
 extern void intel_crt_init(struct drm_device *dev);
 extern void intel_hdmi_init(struct drm_device *dev, int sdvox_reg);
 void intel_dip_infoframe_csum(struct dip_infoframe *avi_if);

drivers/gpu/drm/i915/intel_hdmi.c

@@ -41,6 +41,7 @@ struct intel_hdmi {
 	struct intel_encoder base;
 	u32 sdvox_reg;
 	int ddc_bus;
+	uint32_t color_range;
 	bool has_hdmi_sink;
 	bool has_audio;
 	int force_audio;
@@ -124,6 +125,7 @@ static void intel_hdmi_mode_set(struct drm_encoder *encoder,
 	u32 sdvox;
 
 	sdvox = SDVO_ENCODING_HDMI | SDVO_BORDER_ENABLE;
+	sdvox |= intel_hdmi->color_range;
 	if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
 		sdvox |= SDVO_VSYNC_ACTIVE_HIGH;
 	if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
@@ -278,6 +280,7 @@ intel_hdmi_set_property(struct drm_connector *connector,
 		      uint64_t val)
 {
 	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
 	int ret;
 
 	ret = drm_connector_property_set_value(connector, property, val);
@@ -305,6 +308,14 @@ intel_hdmi_set_property(struct drm_connector *connector,
 		goto done;
 	}
 
+	if (property == dev_priv->broadcast_rgb_property) {
+		if (val == !!intel_hdmi->color_range)
+			return 0;
+
+		intel_hdmi->color_range = val ? SDVO_COLOR_RANGE_16_235 : 0;
+		goto done;
+	}
+
 	return -EINVAL;
 
 done:
@@ -363,6 +374,8 @@ intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *c
 		intel_hdmi->force_audio_property->values[1] = 1;
 		drm_connector_attach_property(connector, intel_hdmi->force_audio_property, 0);
 	}
+
+	intel_attach_broadcast_rgb_property(connector);
 }
 
 void intel_hdmi_init(struct drm_device *dev, int sdvox_reg)

drivers/gpu/drm/i915/intel_modes.c

@@ -80,3 +80,33 @@ int intel_ddc_get_modes(struct drm_connector *connector,
 
 	return ret;
 }
+
+static const char *broadcast_rgb_names[] = {
+	"Full",
+	"Limited 16:235",
+};
+
+void
+intel_attach_broadcast_rgb_property(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_property *prop;
+	int i;
+
+	prop = dev_priv->broadcast_rgb_property;
+	if (prop == NULL) {
+		prop = drm_property_create(dev, DRM_MODE_PROP_ENUM,
+					   "Broadcast RGB",
+					   ARRAY_SIZE(broadcast_rgb_names));
+		if (prop == NULL)
+			return;
+
+		for (i = 0; i < ARRAY_SIZE(broadcast_rgb_names); i++)
+			drm_property_add_enum(prop, i, i, broadcast_rgb_names[i]);
+
+		dev_priv->broadcast_rgb_property = prop;
+	}
+
+	drm_connector_attach_property(connector, prop, 0);
+}

drivers/gpu/drm/i915/intel_sdvo.c

@@ -92,6 +92,12 @@ struct intel_sdvo {
 	*/
 	uint16_t attached_output;
 
+	/**
+	 * This is used to select the color range of RBG outputs in HDMI mode.
+	 * It is only valid when using TMDS encoding and 8 bit per color mode.
+	 */
+	uint32_t color_range;
+
 	/**
 	 * This is set if we're going to treat the device as TV-out.
 	 *
@@ -1056,6 +1062,8 @@ static void intel_sdvo_mode_set(struct drm_encoder *encoder,
 	/* Set the SDVO control regs. */
 	if (INTEL_INFO(dev)->gen >= 4) {
 		sdvox = 0;
+		if (intel_sdvo->is_hdmi)
+			sdvox |= intel_sdvo->color_range;
 		if (INTEL_INFO(dev)->gen < 5)
 			sdvox |= SDVO_BORDER_ENABLE;
 		if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
@@ -1695,6 +1703,7 @@ intel_sdvo_set_property(struct drm_connector *connector,
 {
 	struct intel_sdvo *intel_sdvo = intel_attached_sdvo(connector);
 	struct intel_sdvo_connector *intel_sdvo_connector = to_intel_sdvo_connector(connector);
+	struct drm_i915_private *dev_priv = connector->dev->dev_private;
 	uint16_t temp_value;
 	uint8_t cmd;
 	int ret;
@@ -1724,6 +1733,14 @@ intel_sdvo_set_property(struct drm_connector *connector,
 		goto done;
 	}
 
+	if (property == dev_priv->broadcast_rgb_property) {
+		if (val == !!intel_sdvo->color_range)
+			return 0;
+
+		intel_sdvo->color_range = val ? SDVO_COLOR_RANGE_16_235 : 0;
+		goto done;
+	}
+
 #define CHECK_PROPERTY(name, NAME) \
 	if (intel_sdvo_connector->name == property) { \
 		if (intel_sdvo_connector->cur_##name == temp_value) return 0; \
@@ -2028,6 +2045,9 @@ intel_sdvo_add_hdmi_properties(struct intel_sdvo_connector *connector)
 		drm_connector_attach_property(&connector->base.base,
 					      connector->force_audio_property, 0);
 	}
+
+	if (INTEL_INFO(dev)->gen >= 4 && IS_MOBILE(dev))
+		intel_attach_broadcast_rgb_property(&connector->base.base);
 }
 
 static bool