[PATCH v3 26/33] drm/vkms: Introduce configfs for connector supported colorspace

Louis Chauvet
2025-12-22T10:12:37Z

Add the attribute supported_colorspaces to configure the supported
colorspace of a connector. It will allows emulating some HDR features of
displays. This feature is only supported for HDMI, DP and eDP connectors.

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Documentation/ABI/testing/configfs-vkms | 8 +++++++
Documentation/gpu/vkms.rst | 7 +++++-
drivers/gpu/drm/vkms/vkms_configfs.c | 40 +++++++++++++++++++++++++++++++++
3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/configfs-vkms b/Documentation/ABI/testing/configfs-vkms
index 5452140cc508..f750e616be54 100644
--- a/Documentation/ABI/testing/configfs-vkms
+++ b/Documentation/ABI/testing/configfs-vkms
@@ -40,6 +40,14 @@ Description:
Type of the connector. Possible values match those
exposed by the "type" field in drm_connector.

+What: /sys/kernel/config/vkms/<device>/connectors/<connector>/supported_colorspaces
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Supported colorspaces for HDMI, DP, and eDP connectors.
+ Value is a bitfield, where 0x1 = NO_DATA, 0x2 = SMPTE_170M_YCC,
+ etc. See enum drm_colorspace for full list.
+
What: /sys/kernel/config/vkms/<device>/connectors/<connector>/possible_encoders
Date: Nov 2025
Contact: dri-devel@lists.freedesktop.org
diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index 41c6f4733663..1c4a8023374c 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -138,11 +138,16 @@ Last but not least, create one or more connectors::

sudo mkdir /config/vkms/my-vkms/connectors/connector0

-Connectors have 2 configurable attribute:
+Connectors have 3 configurable attribute:

- status: Connection status: 1 connected, 2 disconnected, 3 unknown (same values
as those exposed by the "status" property of a connector)
- type: Type of connector. Same values as exposed by the "type" field in drm_connector.
+- supported_colorspaces: Supported colorspaces values for HDMI, DP and eDP connectors.
+ If supported_colorspaces is not 0, the HDR_OUTPUT_METADATA will also be created.
+ Value is a bitfield, 0x1 = NO_DATA, 0x2 = SMPTE_170M_YCC... see enum drm_colorspace
+ for full list.
+

To finish the configuration, link the different pipeline items::

diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index d6a85d6c466f..90bf6e6995ae 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -1233,12 +1233,52 @@ static ssize_t connector_type_store(struct config_item *item,
return count;
}

+static ssize_t connector_supported_colorspaces_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_connector *connector;
+ int colorspaces;
+
+ connector = connector_item_to_vkms_configfs_connector(item);
+
+ scoped_guard(mutex, &connector->dev->lock)
+ colorspaces = vkms_config_connector_get_supported_colorspaces(connector->config);
+
+ return sprintf(page, "%u", colorspaces);
+}
+
+static ssize_t connector_supported_colorspaces_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct vkms_configfs_connector *connector;
+ int val, ret;
+
+ connector = connector_item_to_vkms_configfs_connector(item);
+
+ ret = kstrtouint(page, 10, &val);
+ if (ret)
+ return ret;
+
+ if ((val & -BIT(DRM_MODE_COLORIMETRY_COUNT)) != 0)
+ return -EINVAL;
+
+ scoped_guard(mutex, &connector->dev->lock) {
+ if (connector->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_connector_set_supported_colorspaces(connector->config, val);
+ }
+
+ return count;
+}
+
CONFIGFS_ATTR(connector_, status);
CONFIGFS_ATTR(connector_, type);
+CONFIGFS_ATTR(connector_, supported_colorspaces);

static struct configfs_attribute *connector_item_attrs[] = {
&connector_attr_status,
&connector_attr_type,
+ &connector_attr_supported_colorspaces,
NULL,
};

--
2.51.2