[RFC 1/2] drm/i915: Add connector property to force bpc

["Sripada, Radhakrishna" <radhakrishna.sripada@intel.com>]

Currently the user space does not have a way to force the bpc. The
default bpc to be programmed is decided by the driver and is run
against connector limitations. Creating a new property for the userspace
to recommend a certain color depth while scanning out the pixels.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h     |  7 +++++++
 drivers/gpu/drm/i915/intel_atomic.c |  7 +++++++
 drivers/gpu/drm/i915/intel_drv.h    |  2 ++
 drivers/gpu/drm/i915/intel_hdmi.c   |  1 +
 drivers/gpu/drm/i915/intel_modes.c  | 29 +++++++++++++++++++++++++++++
 5 files changed, 46 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2783f07c6fc4..e58856f7b08a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2521,6 +2521,7 @@ struct drm_i915_private {
 
 	struct drm_property *broadcast_rgb_property;
 	struct drm_property *force_audio_property;
+	struct drm_property *force_bpc_property;
 
 	/* hda/i915 audio component */
 	struct i915_audio_component *audio_component;
@@ -2858,6 +2859,12 @@ enum hdmi_force_audio {
 	HDMI_AUDIO_ON,			/* force turn on HDMI audio */
 };
 
+enum connector_force_bpc {
+	INTEL_FORCE_BPC_AUTO,
+	INTEL_FORCE_BPC_8,
+	INTEL_FORCE_BPC_10,
+	INTEL_FORCE_BPC_12,
+};
 #define I915_GTT_OFFSET_NONE ((u32)-1)
 
 /*
diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
index 36d4e635e4ce..10a74669f49a 100644
--- a/drivers/gpu/drm/i915/intel_atomic.c
+++ b/drivers/gpu/drm/i915/intel_atomic.c
@@ -58,6 +58,8 @@ int intel_digital_connector_atomic_get_property(struct drm_connector *connector,
 		*val = intel_conn_state->force_audio;
 	else if (property == dev_priv->broadcast_rgb_property)
 		*val = intel_conn_state->broadcast_rgb;
+	else if (property == dev_priv->force_bpc_property)
+		*val = intel_conn_state->force_bpc;
 	else {
 		DRM_DEBUG_ATOMIC("Unknown property %s\n", property->name);
 		return -EINVAL;
@@ -95,6 +97,11 @@ int intel_digital_connector_atomic_set_property(struct drm_connector *connector,
 		return 0;
 	}
 
+	if (property == dev_priv->force_bpc_property) {
+		intel_conn_state->force_bpc = val;
+		return 0;
+	}
+
 	DRM_DEBUG_ATOMIC("Unknown property %s\n", property->name);
 	return -EINVAL;
 }
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 77117e188b04..654e76d19514 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -341,6 +341,7 @@ struct intel_digital_connector_state {
 
 	enum hdmi_force_audio force_audio;
 	int broadcast_rgb;
+	enum connector_force_bpc force_bpc;
 };
 
 #define to_intel_digital_connector_state(x) container_of(x, struct intel_digital_connector_state, base)
@@ -1708,6 +1709,7 @@ int intel_ddc_get_modes(struct drm_connector *c, struct i2c_adapter *adapter);
 void intel_attach_force_audio_property(struct drm_connector *connector);
 void intel_attach_broadcast_rgb_property(struct drm_connector *connector);
 void intel_attach_aspect_ratio_property(struct drm_connector *connector);
+void intel_attach_force_bpc_property(struct drm_connector *connector);
 
 
 /* intel_overlay.c */
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 50214e342401..a2d6d97cc730 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1798,6 +1798,7 @@ 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_attach_aspect_ratio_property(connector);
+	intel_attach_force_bpc_property(connector);
 	connector->state->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_modes.c b/drivers/gpu/drm/i915/intel_modes.c
index 28a778b785ac..d7be44a951e8 100644
--- a/drivers/gpu/drm/i915/intel_modes.c
+++ b/drivers/gpu/drm/i915/intel_modes.c
@@ -151,3 +151,32 @@ intel_attach_aspect_ratio_property(struct drm_connector *connector)
 			connector->dev->mode_config.aspect_ratio_property,
 			DRM_MODE_PICTURE_ASPECT_NONE);
 }
+
+static const struct drm_prop_enum_list force_bpc_names[] = {
+	{ INTEL_FORCE_BPC_AUTO, "Automatic" },
+	{ INTEL_FORCE_BPC_8, "8 bpc" },
+	{ INTEL_FORCE_BPC_10, "10 bpc" },
+	{ INTEL_FORCE_BPC_12, "12 bpc" },
+};
+
+void
+intel_attach_force_bpc_property(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_property *prop;
+
+	prop = dev_priv->force_bpc_property;
+	if (prop == NULL) {
+		prop = drm_property_create_enum(dev, DRM_MODE_PROP_ENUM,
+					   "bpc",
+					   force_bpc_names,
+					   ARRAY_SIZE(force_bpc_names));
+		if (prop == NULL)
+			return;
+
+		dev_priv->force_bpc_property = prop;
+	}
+
+	drm_object_attach_property(&connector->base, prop, 0);
+}
-- 
2.9.3

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