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>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_modes.c b/drivers/gpu/drm/i915/intel_modes.c
index f70b7cf32bf..9034dd8f33c 100644
--- a/drivers/gpu/drm/i915/intel_modes.c
+++ b/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);
+}