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, 25 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index f194d756a58c..db67be66639b 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -768,6 +768,15 @@ bool intel_hdmi_mode_fixup(struct drm_encoder *encoder,
 {
         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;
 
@@ -912,10 +921,21 @@ intel_hdmi_set_property(struct drm_connector *connector,
         }
 
         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;
         }
 
@@ -964,6 +984,7 @@ intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *c
 {
         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,