[PATCH v8 02/20] drm: Add new general DRM property "color format"
Nicolas Frattaroli
nicolas.frattaroli at collabora.com
Mon Feb 16 05:01:16 PST 2026
From: Andri Yngvason <andri at 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 at tuxedocomputers.com>
Signed-off-by: Andri Yngvason <andri at yngvason.is>
Signed-off-by: Marius Vlad <marius.vlad at collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli at collabora.com>
---
drivers/gpu/drm/drm_atomic_helper.c | 5 ++
drivers/gpu/drm/drm_atomic_uapi.c | 11 +++
drivers/gpu/drm/drm_connector.c | 150 ++++++++++++++++++++++++++++++++++++
include/drm/drm_connector.h | 116 ++++++++++++++++++++++++++--
4 files changed, 277 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index d422f79b96db..d7e902ce5d2d 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 dc013a22bf26..907dd3374533 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 >= DRM_COLOR_FORMAT_ENUM_NUM) {
+ 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 aec05adbc889..4d85add60d92 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1359,6 +1359,32 @@ static const char * const colorspace_names[] = {
[DRM_MODE_COLORIMETRY_BT601_YCC] = "BT601_YCC",
};
+/**
+ * drm_get_color_format_name - return a string for color format
+ * @color_fmt: color format to return the name of
+ *
+ * Returns a string constant matching the format's name, or NULL if no match
+ * is found.
+ */
+const char *drm_get_color_format_name(enum drm_color_format_enum color_fmt)
+{
+ switch (color_fmt) {
+ case DRM_COLOR_FORMAT_ENUM_AUTO:
+ return "AUTO";
+ case DRM_COLOR_FORMAT_ENUM_RGB444:
+ return "RGB";
+ case DRM_COLOR_FORMAT_ENUM_YCBCR444:
+ return "YUV 4:4:4";
+ case DRM_COLOR_FORMAT_ENUM_YCBCR422:
+ return "YUV 4:2:2";
+ case DRM_COLOR_FORMAT_ENUM_YCBCR420:
+ return "YUV 4:2:0";
+ default:
+ return NULL;
+ }
+}
+EXPORT_SYMBOL(drm_get_color_format_name);
+
/**
* drm_get_colorspace_name - return a string for color encoding
* @colorspace: color space to compute name of
@@ -1388,6 +1414,20 @@ static const u32 hdmi_colorspaces =
BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_D65) |
BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_THEATER);
+/* already bit-shifted */
+static const u32 hdmi_colorformats =
+ DRM_COLOR_FORMAT_RGB444 |
+ DRM_COLOR_FORMAT_YCBCR444 |
+ DRM_COLOR_FORMAT_YCBCR422 |
+ DRM_COLOR_FORMAT_YCBCR420;
+
+/* already bit-shifted */
+static const u32 dp_colorformats =
+ DRM_COLOR_FORMAT_RGB444 |
+ DRM_COLOR_FORMAT_YCBCR444 |
+ DRM_COLOR_FORMAT_YCBCR422 |
+ DRM_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 +2689,97 @@ 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 &enum drm_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,
+ u32 supported_color_formats)
+{
+ struct drm_device *dev = connector->dev;
+ struct drm_prop_enum_list enum_list[DRM_COLOR_FORMAT_ENUM_NUM];
+ enum drm_color_format_enum fmt_e;
+ unsigned int len = 1;
+ unsigned int i = 1;
+ u32 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 & ~DRM_COLOR_FORMAT_ALL) {
+ 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 = drm_get_color_format_name(DRM_COLOR_FORMAT_ENUM_AUTO);
+ enum_list[0].type = DRM_COLOR_FORMAT_ENUM_AUTO;
+
+ while (supported_color_formats) {
+ fmt = BIT(i - 1);
+ if (supported_color_formats & fmt) {
+ supported_color_formats ^= fmt;
+ fmt_e = drm_color_format_to_enum(fmt);
+ if (fmt_e != DRM_COLOR_FORMAT_ENUM_INVALID) {
+ enum_list[len].name = drm_get_color_format_name(fmt_e);
+ enum_list[len].type = fmt_e;
+ len++;
+ } else {
+ drm_warn(dev,
+ "Unknown supported format 0x%x on [CONNECTOR:%d:%s]\n",
+ fmt, connector->base.id, connector->name);
+ }
+ }
+ i++;
+ }
+
+ connector->color_format_property =
+ drm_property_create_enum(dev, DRM_MODE_PROP_ENUM, "color format",
+ enum_list, len);
+
+ 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 +2997,25 @@ 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 "force color format" property
+ * @connector: connector to attach force color format property on.
+ *
+ * This is used to add support for selecting 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_COLOR_FORMAT_ENUM_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 c18be8c19de0..18bd875b6918 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -556,6 +556,97 @@ enum drm_colorspace {
DRM_MODE_COLORIMETRY_COUNT
};
+/**
+ * enum drm_color_format_enum - color model description
+ *
+ * This enum is a high-level description of the component makeup of the image
+ * data. It says nothing about how the components are ordered or how many bits
+ * they take up (i.e. is unlike MEDIA_BUS_FMT\_ or DRM_FORMAT\_), but
+ * describes the type of components (Luminance-Chrominance vs. RGB) and the
+ * sub-sampling.
+ *
+ * &enum drm_color_format_enum makes statements about the same attribute of
+ * an image as the DRM_COLOR_FORMAT\_ bitfields do. Its purpose is to inform
+ * choices made by display protocol specific implementations when it comes to
+ * translating it to e.g. &enum hdmi_colorspace or &enum dp_pixelformat, both
+ * of which also describe the same attribute of the image at the same level of
+ * specificity.
+ *
+ * In precise terms, this enum describes a color model. It makes no statements
+ * about the primaries, gamma, or current phase of the moon used in conversion
+ * from one to the other. Furthermore, it also makes no statements about the
+ * order of components (e.g. RGB vs. BGR), their depth in bits, or their binary
+ * packing.
+ */
+enum drm_color_format_enum {
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_AUTO: The choice of format is left up to the
+ * display protocol implementation. All implementations of the same
+ * display protocol (e.g. HDMI) are supposed to behave the same way,
+ * though display protocols may choose to behave differently compared to
+ * each other (e.g. HDMI's "AUTO" does not have to match DP's "AUTO").
+ *
+ * Implementations may rely on @DRM_COLOR_FORMAT_ENUM_AUTO to be falsy.
+ */
+ DRM_COLOR_FORMAT_ENUM_AUTO = 0,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_RGB444: Image components are encoded as RGB
+ * values of equal resolution.
+ */
+ DRM_COLOR_FORMAT_ENUM_RGB444,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_YCBCR444: Image components are encoded as
+ * luminance and chrominance of equal resolution.
+ */
+ DRM_COLOR_FORMAT_ENUM_YCBCR444,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_YCBCR422: Image components are encoded as
+ * luminance and chrominance with the chrominance components having half
+ * the horizontal resolution.
+ */
+ DRM_COLOR_FORMAT_ENUM_YCBCR422,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_YCBCR420: Image components are encoded as
+ * luminance and chrominance with the chrominance components having half
+ * the horizontal and vertical resolution.
+ */
+ DRM_COLOR_FORMAT_ENUM_YCBCR420,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_NUM: The number of valid color format values
+ * in this enum. Itself not a valid color format.
+ */
+ DRM_COLOR_FORMAT_ENUM_NUM,
+
+ /**
+ * @DRM_COLOR_FORMAT_ENUM_INVALID: Error return value for conversion
+ * functions encountering unexpected inputs.
+ */
+ DRM_COLOR_FORMAT_ENUM_INVALID = -EINVAL,
+};
+
+/*
+ * Constants for specifying bit masks for e.g. providing a list of supported
+ * color formats as a single integer.
+ */
+#define DRM_COLOR_FORMAT_RGB444 BIT(0)
+#define DRM_COLOR_FORMAT_YCBCR444 BIT(1)
+#define DRM_COLOR_FORMAT_YCBCR422 BIT(2)
+#define DRM_COLOR_FORMAT_YCBCR420 BIT(3)
+
+/*
+ * Mask of all DRM_COLOR_FORMAT\_ constants. When adding new color formats,
+ * they must be part of this define.
+ */
+#define DRM_COLOR_FORMAT_ALL (DRM_COLOR_FORMAT_RGB444 | \
+ DRM_COLOR_FORMAT_YCBCR444 | \
+ DRM_COLOR_FORMAT_YCBCR422 | \
+ DRM_COLOR_FORMAT_YCBCR420)
+
/**
* enum drm_bus_flags - bus_flags info for &drm_display_info
*
@@ -699,11 +790,6 @@ struct drm_display_info {
*/
enum subpixel_order subpixel_order;
-#define DRM_COLOR_FORMAT_RGB444 (1<<0)
-#define DRM_COLOR_FORMAT_YCBCR444 (1<<1)
-#define DRM_COLOR_FORMAT_YCBCR422 (1<<2)
-#define DRM_COLOR_FORMAT_YCBCR420 (1<<3)
-
/**
* @panel_orientation: Read only connector property for built-in panels,
* indicating the orientation of the panel vs the device's casing.
@@ -1107,6 +1193,13 @@ 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_color_format_enum color_format;
+
/**
* @writeback_job: Writeback job for writeback connectors
*
@@ -2105,6 +2198,12 @@ 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:
*
@@ -2507,6 +2606,9 @@ 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,
+ u32 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);
@@ -2588,6 +2690,10 @@ 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);
+
+const char *drm_get_color_format_name(enum drm_color_format_enum color_fmt);
+
/**
* drm_for_each_connector_iter - connector_list iterator macro
* @connector: &struct drm_connector pointer used as cursor
--
2.53.0
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