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 <paulo.r.zanoni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 31 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 3b8491a..3e34a35 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -103,6 +103,7 @@ struct intel_sdvo {
 	 * 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.
@@ -1064,6 +1065,15 @@ static bool intel_sdvo_mode_fixup(struct drm_encoder *encoder,
 	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;
 
@@ -1900,10 +1910,21 @@ intel_sdvo_set_property(struct drm_connector *connector,
 	}
 
 	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;
 	}
 
@@ -2200,13 +2221,16 @@ intel_sdvo_connector_init(struct intel_sdvo_connector *connector,
 }
 
 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
@@ -2254,7 +2278,7 @@ intel_sdvo_dvi_init(struct intel_sdvo *intel_sdvo, int device)
 
 	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;
 }