[PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding

Louis Chauvet
2025-10-29T14:37:14Z

To allows the userspace to test many hardware configuration, introduce a
new interface to configure the available color encoding per planes. VKMS
supports multiple color encoding, so the userspace can choose any
combination.

The supported color encoding are configured by writing a color encoding
bitmask to the file `supported_color_encoding` and the default color
encoding is chosen by writing a color encoding bitmask to
`default_color_encoding`.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Documentation/gpu/vkms.rst | 7 ++-
drivers/gpu/drm/vkms/vkms_configfs.c | 98 ++++++++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index eac1a942d6c4..dab6811687a2 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -87,7 +87,7 @@ Start by creating one or more planes::

sudo mkdir /config/vkms/my-vkms/planes/plane0

-Planes have 4 configurable attributes:
+Planes have 6 configurable attributes:

- type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
exposed by the "type" property of a plane)
@@ -97,6 +97,11 @@ Planes have 4 configurable attributes:
(same values as those exposed by the "rotation" property of a plane)
- default_rotation: Default rotation presented to the userspace, same values as
possible_rotations.
+- supported_color_encoding: Available encoding for a plane, as a bitmask:
+ 0x01 YCBCR_BT601, 0x02: YCBCR_BT709, 0x04 YCBCR_BT2020 (same values as those exposed
+ by the COLOR_ENCODING property of a plane)
+- default_color_encoding: Default color encoding presented to the userspace, same
+ values as supported_color_encoding

Continue by creating one or more CRTCs::

diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 7cc8ba315ef0..ee2e8d141f9e 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -439,16 +439,114 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
return count;
}

+static ssize_t plane_supported_color_encodings_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int supported_color_encoding;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ supported_color_encoding = vkms_config_plane_get_supported_color_encodings(plane->config);
+ }
+
+ return sprintf(page, "%u", supported_color_encoding);
+}
+
+static ssize_t plane_supported_color_encodings_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
+ int ret, val = 0;
+
+ ret = kstrtouint(page, 10, &val);
+ if (ret)
+ return ret;
+
+ /* Should be a supported value */
+ if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
+ BIT(DRM_COLOR_YCBCR_BT709) |
+ BIT(DRM_COLOR_YCBCR_BT2020)))
+ return -EINVAL;
+ /* Should at least provide one color range */
+ if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
+ BIT(DRM_COLOR_YCBCR_BT709) |
+ BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ /* Ensures that the default rotation is included in supported rotation */
+ if (plane->dev->enabled)
+ return -EINVAL;
+
+ vkms_config_plane_set_supported_color_encodings(plane->config, val);
+ }
+
+ return count;
+}
+
+/* Plane default_color_encoding : vkms/<device>/planes/<plane>/default_color_encoding */
+
+static ssize_t plane_default_color_encoding_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int default_color_encoding;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ default_color_encoding = vkms_config_plane_get_default_color_encoding(plane->config);
+ }
+
+ return sprintf(page, "%u", default_color_encoding);
+}
+
+static ssize_t plane_default_color_encoding_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
+ int ret, val = 0;
+
+ ret = kstrtouint(page, 10, &val);
+ if (ret)
+ return ret;
+
+ /* Should be a supported value */
+ if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
+ BIT(DRM_COLOR_YCBCR_BT709) |
+ BIT(DRM_COLOR_YCBCR_BT2020)))
+ return -EINVAL;
+ /* Should at least provide one color range */
+ if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
+ BIT(DRM_COLOR_YCBCR_BT709) |
+ BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ /* Ensures that the default rotation is included in supported rotation */
+ if (plane->dev->enabled)
+ return -EINVAL;
+
+ vkms_config_plane_set_default_color_encoding(plane->config, val);
+ }
+
+ return count;
+}
+
CONFIGFS_ATTR(plane_, type);
CONFIGFS_ATTR(plane_, name);
CONFIGFS_ATTR(plane_, supported_rotations);
CONFIGFS_ATTR(plane_, default_rotation);
+CONFIGFS_ATTR(plane_, supported_color_encodings);
+CONFIGFS_ATTR(plane_, default_color_encoding);

static struct configfs_attribute *plane_item_attrs[] = {
&plane_attr_type,
&plane_attr_name,
&plane_attr_supported_rotations,
&plane_attr_default_rotation,
+ &plane_attr_supported_color_encodings,
+ &plane_attr_default_color_encoding,
NULL,
};

--
2.51.0