drm/i915: Add "Automatic" mode for the "Broadcast RGB" property

Add a new "Automatic" mode to the "Broadcast RGB" range property.
When selected the driver automagically selects between full range and
limited range output.

Based on CEA-861 [1] guidelines, limited range output is selected if the
mode is a CEA mode, except 640x480. Otherwise full range output is used.
Additionally DVI monitors should most likely default to full range
always.

As per DP1.2a [2] DisplayPort should always use full range for 18bpp, and
otherwise will follow CEA-861 rules.

NOTE: The default value for the property will now be "Automatic"
so some people may be affected in case they're relying on the
current full range default.

[1] CEA-861-E - 5.1 Default Encoding Parameters
[2] VESA DisplayPort Ver.1.2a - 5.1.1.1 Video Colorimetry

v2: Use has_hdmi_sink to check if a HDMI monitor is present
v3: Add information about relevant spec chapters

Reviewed-by: Paulo Zanoni <[e-mail]>
Signed-off-by: Ville Syrjälä <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/i915/i915_drv.h

···
 #define POSTING_READ(reg)	(void)I915_READ_NOTRACE(reg)
 #define POSTING_READ16(reg)	(void)I915_READ16_NOTRACE(reg)
 
+/* "Broadcast RGB" property */
+#define INTEL_BROADCAST_RGB_AUTO 0
+#define INTEL_BROADCAST_RGB_FULL 1
+#define INTEL_BROADCAST_RGB_LIMITED 2
 
 #endif

drivers/gpu/drm/i915/intel_dp.c

···
 
 	bpp = adjusted_mode->private_flags & INTEL_MODE_DP_FORCE_6BPC ? 18 : 24;
 
+	if (intel_dp->color_range_auto) {
+		/*
+		 * See:
+		 * CEA-861-E - 5.1 Default Encoding Parameters
+		 * VESA DisplayPort Ver.1.2a - 5.1.1.1 Video Colorimetry
+		 */
+		if (bpp != 18 && drm_mode_cea_vic(adjusted_mode) > 1)
+			intel_dp->color_range = DP_COLOR_RANGE_16_235;
+		else
+			intel_dp->color_range = 0;
+	}
+
 	if (intel_dp->color_range)
 		adjusted_mode->private_flags |= INTEL_MODE_LIMITED_COLOR_RANGE;
 
···
 	}
 
 	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;
+		switch (val) {
+		case INTEL_BROADCAST_RGB_AUTO:
+			intel_dp->color_range_auto = true;
+			break;
+		case INTEL_BROADCAST_RGB_FULL:
+			intel_dp->color_range_auto = false;
+			intel_dp->color_range = 0;
+			break;
+		case INTEL_BROADCAST_RGB_LIMITED:
+			intel_dp->color_range_auto = false;
+			intel_dp->color_range = DP_COLOR_RANGE_16_235;
+			break;
+		default:
+			return -EINVAL;
+		}
 		goto done;
 	}
 
···
 
 	intel_attach_force_audio_property(connector);
 	intel_attach_broadcast_rgb_property(connector);
+	intel_dp->color_range_auto = true;
 
 	if (is_edp(intel_dp)) {
 		drm_mode_create_scaling_mode_property(connector->dev);

drivers/gpu/drm/i915/intel_drv.h

···
 	u32 sdvox_reg;
 	int ddc_bus;
 	uint32_t color_range;
+	bool color_range_auto;
 	bool has_hdmi_sink;
 	bool has_audio;
 	enum hdmi_force_audio force_audio;
···
 	bool has_audio;
 	enum hdmi_force_audio force_audio;
 	uint32_t color_range;
+	bool color_range_auto;
 	uint8_t link_bw;
 	uint8_t lane_count;
 	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];

drivers/gpu/drm/i915/intel_hdmi.c

···
 {
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 
+	if (intel_hdmi->color_range_auto) {
+		/* See CEA-861-E - 5.1 Default Encoding Parameters */
+		if (intel_hdmi->has_hdmi_sink &&
+		    drm_mode_cea_vic(adjusted_mode) > 1)
+			intel_hdmi->color_range = SDVO_COLOR_RANGE_16_235;
+		else
+			intel_hdmi->color_range = 0;
+	}
+
 	if (intel_hdmi->color_range)
 		adjusted_mode->private_flags |= INTEL_MODE_LIMITED_COLOR_RANGE;
 
···
 	}
 
 	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;
+		switch (val) {
+		case INTEL_BROADCAST_RGB_AUTO:
+			intel_hdmi->color_range_auto = true;
+			break;
+		case INTEL_BROADCAST_RGB_FULL:
+			intel_hdmi->color_range_auto = false;
+			intel_hdmi->color_range = 0;
+			break;
+		case INTEL_BROADCAST_RGB_LIMITED:
+			intel_hdmi->color_range_auto = false;
+			intel_hdmi->color_range = SDVO_COLOR_RANGE_16_235;
+			break;
+		default:
+			return -EINVAL;
+		}
 		goto done;
 	}
 
···
 {
 	intel_attach_force_audio_property(connector);
 	intel_attach_broadcast_rgb_property(connector);
+	intel_hdmi->color_range_auto = true;
 }
 
 void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,

drivers/gpu/drm/i915/intel_modes.c

···
 }
 
 static const struct drm_prop_enum_list broadcast_rgb_names[] = {
-	{ 0, "Full" },
-	{ 1, "Limited 16:235" },
+	{ INTEL_BROADCAST_RGB_AUTO, "Automatic" },
+	{ INTEL_BROADCAST_RGB_FULL, "Full" },
+	{ INTEL_BROADCAST_RGB_LIMITED, "Limited 16:235" },
 };
 
 void

drivers/gpu/drm/i915/intel_sdvo.c

···
 	 * It is only valid when using TMDS encoding and 8 bit per color mode.
 	 */
 	uint32_t color_range;
+	bool color_range_auto;
 
 	/**
 	 * This is set if we're going to treat the device as TV-out.
···
 	multiplier = intel_sdvo_get_pixel_multiplier(adjusted_mode);
 	intel_mode_set_pixel_multiplier(adjusted_mode, multiplier);
 
+	if (intel_sdvo->color_range_auto) {
+		/* See CEA-861-E - 5.1 Default Encoding Parameters */
+		if (intel_sdvo->has_hdmi_monitor &&
+		    drm_mode_cea_vic(adjusted_mode) > 1)
+			intel_sdvo->color_range = SDVO_COLOR_RANGE_16_235;
+		else
+			intel_sdvo->color_range = 0;
+	}
+
 	if (intel_sdvo->color_range)
 		adjusted_mode->private_flags |= INTEL_MODE_LIMITED_COLOR_RANGE;
 
···
 	}
 
 	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;
+		switch (val) {
+		case INTEL_BROADCAST_RGB_AUTO:
+			intel_sdvo->color_range_auto = true;
+			break;
+		case INTEL_BROADCAST_RGB_FULL:
+			intel_sdvo->color_range_auto = false;
+			intel_sdvo->color_range = 0;
+			break;
+		case INTEL_BROADCAST_RGB_LIMITED:
+			intel_sdvo->color_range_auto = false;
+			intel_sdvo->color_range = SDVO_COLOR_RANGE_16_235;
+			break;
+		default:
+			return -EINVAL;
+		}
 		goto done;
 	}
 
···
 }
 
 static void
-intel_sdvo_add_hdmi_properties(struct intel_sdvo_connector *connector)
+intel_sdvo_add_hdmi_properties(struct intel_sdvo *intel_sdvo,
+			       struct intel_sdvo_connector *connector)
 {
 	struct drm_device *dev = connector->base.base.dev;
 
 	intel_attach_force_audio_property(&connector->base.base);
-	if (INTEL_INFO(dev)->gen >= 4 && IS_MOBILE(dev))
+	if (INTEL_INFO(dev)->gen >= 4 && IS_MOBILE(dev)) {
 		intel_attach_broadcast_rgb_property(&connector->base.base);
+		intel_sdvo->color_range_auto = true;
+	}
 }
 
 static bool
···
 
 	intel_sdvo_connector_init(intel_sdvo_connector, intel_sdvo);
 	if (intel_sdvo->is_hdmi)
-		intel_sdvo_add_hdmi_properties(intel_sdvo_connector);
+		intel_sdvo_add_hdmi_properties(intel_sdvo, intel_sdvo_connector);
 
 	return true;
 }