[PATCH RESEND v2 25/32] drm/vkms: Introduce configfs for connector supported colorspace

Louis Chauvet
2025-10-29T14:37:36Z

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.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Documentation/gpu/vkms.rst | 7 ++++++-
drivers/gpu/drm/vkms/vkms_configfs.c | 39 ++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index 99c5cf3dbd78..c762cadac6f4 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 b03e9af569b6..a7f4589403ce 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -1223,12 +1223,51 @@ 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 type;
+
+ connector = connector_item_to_vkms_configfs_connector(item);
+
+ scoped_guard(mutex, &connector->dev->lock)
+ type = vkms_config_connector_get_supported_colorspaces(connector->config);
+
+ return sprintf(page, "%u", type);
+}
+
+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,
};

--
2.51.0