[PATCH v2 05/11] drm: create hdmi output property

[Shashank Sharma <shashank.sharma@intel.com>]

HDMI displays can support various output types, based on
the color space and subsampling type. The possible
outputs from a HDMI 2.0 monitor could be:
 - RGB
 - YCBCR 444
 - YCBCR 422
 - YCBCR 420

This patch adds a drm property, using which, a userspace
can specify its preference, for the HDMI output type.
The output type enums are similar to the mentioned outputs
above. To handle various subsampling of YCBCR output types,
this property allows two special cases:
 - DRM_HDMI_OUTPUT_YCBCR_HQ
This indicates preferred output should be YCBCR output, with highest
subsampling rate by the source/sink, which can be typically:
 - ycbcr444
 - ycbcr422
 - ycbcr420
 - DRM_HDMI_OUTPUT_YCBCR_LQ
This indicates preferred output should be YCBCR output, with lowest
subsampling rate supported by source/sink, which can be:
 - ycbcr420
 - ycbcr422
 - ycbcr444

Default value of the property is set to 0 = RGB, so no changes if you
dont set the property.

V2: Added description for the new variable to address build warning

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
---
 drivers/gpu/drm/drm_atomic.c        |  2 ++
 drivers/gpu/drm/drm_atomic_helper.c |  4 ++++
 drivers/gpu/drm/drm_connector.c     | 32 ++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h         | 18 ++++++++++++++++++
 include/drm/drm_mode_config.h       |  5 +++++
 5 files changed, 61 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index e163701..8c4e040 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1192,6 +1192,8 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
 		state->picture_aspect_ratio = val;
 	} else if (property == connector->scaling_mode_property) {
 		state->scaling_mode = val;
+	} else if (property == config->hdmi_output_property) {
+		state->hdmi_output = val;
 	} else if (connector->funcs->atomic_set_property) {
 		return connector->funcs->atomic_set_property(connector,
 				state, property, val);
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 636e561..86b1780 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -567,6 +567,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 			if (old_connector_state->link_status !=
 			    new_connector_state->link_status)
 				new_crtc_state->connectors_changed = true;
+
+			if (old_connector_state->hdmi_output !=
+			    new_connector_state->hdmi_output)
+				new_crtc_state->connectors_changed = true;
 		}
 
 		if (funcs->atomic_check)
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 5cd61af..f3c5928 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -227,6 +227,11 @@ int drm_connector_init(struct drm_device *dev,
 					      config->edid_property,
 					      0);
 
+	if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL)
+		drm_object_attach_property(&connector->base,
+					   config->hdmi_output_property,
+					   0);
+
 	drm_object_attach_property(&connector->base,
 				      config->dpms_property, 0);
 
@@ -617,6 +622,26 @@ static const struct drm_prop_enum_list drm_link_status_enum_list[] = {
 };
 DRM_ENUM_NAME_FN(drm_get_link_status_name, drm_link_status_enum_list)
 
+static const struct drm_prop_enum_list drm_hdmi_output_enum_list[] = {
+	{ DRM_HDMI_OUTPUT_DEFAULT_RGB, "output_rgb" },
+	{ DRM_HDMI_OUTPUT_YCBCR444, "output_ycbcr444" },
+	{ DRM_HDMI_OUTPUT_YCBCR422, "output_ycbcr422" },
+	{ DRM_HDMI_OUTPUT_YCBCR420, "output_ycbcr420" },
+	{ DRM_HDMI_OUTPUT_YCBCR_HQ, "output_ycbcr_high_subsampling" },
+	{ DRM_HDMI_OUTPUT_YCBCR_LQ, "output_ycbcr_low_subsampling" },
+	{ DRM_HDMI_OUTPUT_INVALID, "invalid_output" },
+};
+
+/**
+ * drm_get_hdmi_output_name - return a string for a given hdmi output enum
+ * @type: enum of output type
+ */
+const char *drm_get_hdmi_output_name(enum drm_hdmi_output_type type)
+{
+	return drm_hdmi_output_enum_list[type].name;
+}
+EXPORT_SYMBOL(drm_get_hdmi_output_name);
+
 /**
  * drm_display_info_set_bus_formats - set the supported bus formats
  * @info: display info to store bus formats in
@@ -789,6 +814,13 @@ int drm_connector_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.link_status_property = prop;
 
+	prop = drm_property_create_enum(dev, 0, "hdmi_output_format",
+					drm_hdmi_output_enum_list,
+					ARRAY_SIZE(drm_hdmi_output_enum_list));
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.hdmi_output_property = prop;
+
 	return 0;
 }
 
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 49cc38c..f77f283 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -313,6 +313,17 @@ struct drm_tv_connector_state {
 	unsigned int hue;
 };
 
+/* HDMI output pixel format */
+enum drm_hdmi_output_type {
+	DRM_HDMI_OUTPUT_DEFAULT_RGB, /* default RGB */
+	DRM_HDMI_OUTPUT_YCBCR444, /* YCBCR 444 */
+	DRM_HDMI_OUTPUT_YCBCR422, /* YCBCR 422 */
+	DRM_HDMI_OUTPUT_YCBCR420, /* YCBCR 420 */
+	DRM_HDMI_OUTPUT_YCBCR_HQ, /* Highest subsampled YUV */
+	DRM_HDMI_OUTPUT_YCBCR_LQ, /* Lowest subsampled YUV */
+	DRM_HDMI_OUTPUT_INVALID, /* Guess what ? */
+};
+
 /**
  * struct drm_connector_state - mutable connector state
  * @connector: backpointer to the connector
@@ -357,6 +368,12 @@ struct drm_connector_state {
 	 * upscaling, mostly used for built-in panels.
 	 */
 	unsigned int scaling_mode;
+
+	/**
+	 * @hdmi_output: Connector property to control the
+	 * HDMI output mode (RGB/YCBCR444/422/420).
+	 */
+	enum drm_hdmi_output_type hdmi_output;
 };
 
 /**
@@ -976,6 +993,7 @@ static inline void drm_connector_unreference(struct drm_connector *connector)
 
 const char *drm_get_connector_status_name(enum drm_connector_status status);
 const char *drm_get_subpixel_order_name(enum subpixel_order order);
+const char *drm_get_hdmi_output_name(enum drm_hdmi_output_type type);
 const char *drm_get_dpms_name(int val);
 const char *drm_get_dvi_i_subconnector_name(int val);
 const char *drm_get_dvi_i_select_name(int val);
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 4298171..1887261 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -740,6 +740,11 @@ struct drm_mode_config {
 	 * the position of the output on the host's screen.
 	 */
 	struct drm_property *suggested_y_property;
+	/**
+	 * @hdmi_output_property: output pixel format from HDMI display
+	 * Default is set for RGB
+	 */
+	struct drm_property *hdmi_output_property;
 
 	/* dumb ioctl parameters */
 	uint32_t preferred_depth, prefer_shadow;
-- 
2.7.4

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