[PATCH v9 02/19] drm: Add new general DRM property "color format"

[Nicolas Frattaroli <nicolas.frattaroli@collabora.com>]

From: Andri Yngvason <andri@yngvason.is>

Add a new general DRM property named "color format" which can be used by
userspace to request the display driver to output a particular color
format.

Possible options are:
    - auto (setup by default, driver internally picks the color format)
    - rgb
    - ycbcr444
    - ycbcr422
    - ycbcr420

Drivers should advertise from this list which formats they support.
Together with this list and EDID data from the sink we should be able
to relay a list of usable color formats to users to pick from.

Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
Signed-off-by: Andri Yngvason <andri@yngvason.is>
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/drm_atomic_helper.c |   5 ++
 drivers/gpu/drm/drm_atomic_uapi.c   |  11 ++++
 drivers/gpu/drm/drm_connector.c     | 124 ++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h         | 103 ++++++++++++++++++++++++++++++
 4 files changed, 243 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 26953ed6b53e..b7753454b777 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -737,6 +737,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 			if (old_connector_state->max_requested_bpc !=
 			    new_connector_state->max_requested_bpc)
 				new_crtc_state->connectors_changed = true;
+
+			if (old_connector_state->color_format !=
+			    new_connector_state->color_format)
+				new_crtc_state->connectors_changed = true;
+
 		}
 
 		if (funcs->atomic_check)
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 87de41fb4459..e7ce79bb161e 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -931,6 +931,15 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector,
 		state->privacy_screen_sw_state = val;
 	} else if (property == connector->broadcast_rgb_property) {
 		state->hdmi.broadcast_rgb = val;
+	} else if (property == connector->color_format_property) {
+		if (val > INT_MAX || !drm_connector_color_format_valid(val)) {
+			drm_dbg_atomic(connector->dev,
+				       "[CONNECTOR:%d:%s] unknown color format %llu\n",
+				       connector->base.id, connector->name, val);
+			return -EINVAL;
+		}
+
+		state->color_format = val;
 	} else if (connector->funcs->atomic_set_property) {
 		return connector->funcs->atomic_set_property(connector,
 				state, property, val);
@@ -1016,6 +1025,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
 		*val = state->privacy_screen_sw_state;
 	} else if (property == connector->broadcast_rgb_property) {
 		*val = state->hdmi.broadcast_rgb;
+	} else if (property == connector->color_format_property) {
+		*val = state->color_format;
 	} else if (connector->funcs->atomic_get_property) {
 		return connector->funcs->atomic_get_property(connector,
 				state, property, val);
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 23dcc504ffe7..a4907e15dfc5 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1388,6 +1388,18 @@ static const u32 hdmi_colorspaces =
 	BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_D65) |
 	BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_THEATER);
 
+static const u32 hdmi_colorformats =
+	BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
+static const u32 dp_colorformats =
+	BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
 /*
  * As per DP 1.4a spec, 2.2.5.7.5 VSC SDP Payload for Pixel Encoding/Colorimetry
  * Format Table 2-120
@@ -2649,6 +2661,99 @@ int drm_mode_create_hdmi_colorspace_property(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_mode_create_hdmi_colorspace_property);
 
+/**
+ * drm_mode_create_color_format_property - create color format property
+ * @connector: connector to create the color format property on
+ * @supported_color_formats: bitmask of bit-shifted &enum drm_output_color_format
+ *                           values the connector supports
+ *
+ * Called by a driver to create a color format property. Must be attached to
+ * the desired connector afterwards.
+ *
+ * @supported_color_formats should only include color formats the connector
+ * type can actually support.
+ *
+ * Returns:
+ * 0 on success, negative errno on error
+ */
+int drm_mode_create_color_format_property(struct drm_connector *connector,
+					  unsigned long supported_color_formats)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_prop_enum_list enum_list[DRM_CONNECTOR_COLOR_FORMAT_COUNT];
+	unsigned int i = 0;
+	unsigned long fmt;
+
+	if (connector->color_format_property)
+		return 0;
+
+	if (!supported_color_formats) {
+		drm_err(dev, "No supported color formats provided on [CONNECTOR:%d:%s]\n",
+			connector->base.id, connector->name);
+		return -EINVAL;
+	}
+
+	if (supported_color_formats & ~GENMASK(DRM_OUTPUT_COLOR_FORMAT_COUNT - 1, 0)) {
+		drm_err(dev, "Unknown color formats provided on [CONNECTOR:%d:%s]\n",
+			connector->base.id, connector->name);
+		return -EINVAL;
+	}
+
+	switch (connector->connector_type) {
+	case DRM_MODE_CONNECTOR_HDMIA:
+	case DRM_MODE_CONNECTOR_HDMIB:
+		if (supported_color_formats & ~hdmi_colorformats) {
+			drm_err(dev, "Color formats not allowed for HDMI on [CONNECTOR:%d:%s]\n",
+				connector->base.id, connector->name);
+			return -EINVAL;
+		}
+		break;
+	case DRM_MODE_CONNECTOR_DisplayPort:
+	case DRM_MODE_CONNECTOR_eDP:
+		if (supported_color_formats & ~dp_colorformats) {
+			drm_err(dev, "Color formats not allowed for DP on [CONNECTOR:%d:%s]\n",
+				connector->base.id, connector->name);
+			return -EINVAL;
+		}
+		break;
+	}
+
+	enum_list[0].name = "AUTO";
+	enum_list[0].type = DRM_CONNECTOR_COLOR_FORMAT_AUTO;
+
+	for_each_set_bit(fmt, &supported_color_formats, DRM_OUTPUT_COLOR_FORMAT_COUNT) {
+		switch (fmt) {
+		case DRM_OUTPUT_COLOR_FORMAT_RGB444:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_RGB444;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR444:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR444;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR422:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR422;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR420:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR420;
+			break;
+		default:
+			drm_warn(dev, "Unknown supported format %ld on [CONNECTOR:%d:%s]\n",
+				 fmt, connector->base.id, connector->name);
+			continue;
+		}
+		enum_list[i].name = drm_hdmi_connector_get_output_format_name(fmt);
+	}
+
+	connector->color_format_property =
+		drm_property_create_enum(dev, DRM_MODE_PROP_ENUM, "color format",
+					 enum_list, i + 1);
+
+	if (!connector->color_format_property)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_mode_create_color_format_property);
+
 /**
  * drm_mode_create_dp_colorspace_property - create dp colorspace property
  * @connector: connector to create the Colorspace property on.
@@ -2866,6 +2971,25 @@ int drm_connector_attach_max_bpc_property(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_connector_attach_max_bpc_property);
 
+/**
+ * drm_connector_attach_color_format_property - attach "color format" property
+ * @connector: connector to attach color format property on.
+ *
+ * This is used to add support for requesting a color format on a connector.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int drm_connector_attach_color_format_property(struct drm_connector *connector)
+{
+	struct drm_property *prop = connector->color_format_property;
+
+	drm_object_attach_property(&connector->base, prop, DRM_CONNECTOR_COLOR_FORMAT_AUTO);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_connector_attach_color_format_property);
+
 /**
  * drm_connector_attach_hdr_output_metadata_property - attach "HDR_OUTPUT_METADA" property
  * @connector: connector to attach the property on.
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 4af91e252fbd..b5bc93856ad1 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -579,6 +579,91 @@ enum drm_output_color_format {
 	DRM_OUTPUT_COLOR_FORMAT_YCBCR420,
 };
 
+/* Do not forget to adjust after modifying &enum drm_output_color_format */
+#define DRM_OUTPUT_COLOR_FORMAT_COUNT 4
+
+/**
+ * enum drm_connector_color_format - Connector Color Format Request
+ *
+ * This enum, unlike &enum drm_output_color_format, is used to specify requests
+ * for a specific color format on a connector through the DRM "color format"
+ * property. The difference is that it has an "AUTO" value to specify that
+ * no specific choice has been made.
+ */
+enum drm_connector_color_format {
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_AUTO: The driver or display protocol
+	 * helpers should pick a suitable color format. All implementations of a
+	 * specific display protocol must behave the same way with "AUTO", but
+	 * different display protocols do not necessarily have the same "AUTO"
+	 * semantics.
+	 *
+	 * For HDMI, "AUTO" picks RGB, but falls back to YCbCr 4:2:0 if the
+	 * bandwidth required for full-scale RGB is not available, or the mode
+	 * is YCbCr 4:2:0-only, as long as the mode and output both support
+	 * YCbCr 4:2:0.
+	 *
+	 * For display protocols other than HDMI, the recursive bridge chain
+	 * format selection picks the first chain of bridge formats that works,
+	 * as has already been the case before the introduction of the "color
+	 * format" property. Non-HDMI bridges should therefore either sort their
+	 * bus output formats by preference, or agree on a unified auto format
+	 * selection logic that's implemented in a common state helper (like
+	 * how HDMI does it).
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_AUTO = 0,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_RGB444: RGB output format
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_RGB444,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR444: YCbCr 4:4:4 output format (ie.
+	 * not subsampled)
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR444,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR422: YCbCr 4:2:2 output format (ie.
+	 * with horizontal subsampling)
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR422,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR420: YCbCr 4:2:0 output format (ie.
+	 * with horizontal and vertical subsampling)
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR420,
+};
+
+/* Do not forget to adjust after modifying &enum drm_connector_color_format */
+#define DRM_CONNECTOR_COLOR_FORMAT_COUNT 5
+
+/**
+ * drm_connector_color_format_valid - Validate drm_connector_color_format value
+ * @fmt: value to check against all values of &enum drm_connector_color_format
+ *
+ * Checks whether the passed in value of @fmt is one of the allowable values in
+ * &enum drm_connector_color_format.
+ *
+ * Returns: %true if it's a valid value for the enum, %false otherwise.
+ */
+static inline bool __pure
+drm_connector_color_format_valid(enum drm_connector_color_format fmt)
+{
+	switch (fmt) {
+	case DRM_CONNECTOR_COLOR_FORMAT_AUTO:
+	case DRM_CONNECTOR_COLOR_FORMAT_RGB444:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR444:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR422:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR420:
+		return true;
+	default:
+		return false;
+	}
+}
+
 const char *
 drm_hdmi_connector_get_output_format_name(enum drm_output_color_format fmt);
 
@@ -1129,6 +1214,13 @@ struct drm_connector_state {
 	 */
 	enum drm_colorspace colorspace;
 
+	/**
+	 * @color_format: State variable for Connector property to request
+	 * color format change on Sink. This is most commonly used to switch
+	 * between RGB to YUV and vice-versa.
+	 */
+	enum drm_connector_color_format color_format;
+
 	/**
 	 * @writeback_job: Writeback job for writeback connectors
 	 *
@@ -2127,6 +2219,12 @@ struct drm_connector {
 	 */
 	struct drm_property *colorspace_property;
 
+	/**
+	 * @color_format_property: Connector property to set the suitable
+	 * color format supported by the sink.
+	 */
+	struct drm_property *color_format_property;
+
 	/**
 	 * @path_blob_ptr:
 	 *
@@ -2529,6 +2627,9 @@ int drm_mode_create_dp_colorspace_property(struct drm_connector *connector,
 int drm_mode_create_content_type_property(struct drm_device *dev);
 int drm_mode_create_suggested_offset_properties(struct drm_device *dev);
 
+int drm_mode_create_color_format_property(struct drm_connector *connector,
+					  unsigned long supported_color_formats);
+
 int drm_connector_set_path_property(struct drm_connector *connector,
 				    const char *path);
 int drm_connector_set_tile_property(struct drm_connector *connector);
@@ -2610,6 +2711,8 @@ bool drm_connector_has_possible_encoder(struct drm_connector *connector,
 					struct drm_encoder *encoder);
 const char *drm_get_colorspace_name(enum drm_colorspace colorspace);
 
+int drm_connector_attach_color_format_property(struct drm_connector *connector);
+
 /**
  * drm_for_each_connector_iter - connector_list iterator macro
  * @connector: &struct drm_connector pointer used as cursor

-- 
2.53.0