[PATCH RESEND v2 15/32] drm/vkms: Introduce configfs for plane color range

Louis Chauvet
2025-10-29T14:37:19Z

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

The supported color ranges are configured by writing a color range bitmask
to the file `supported_color_ranges` and the default color range is
chosen by writing a color encoding bitmask to `default_color_range`.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Documentation/gpu/vkms.rst | 11 ++++-
drivers/gpu/drm/vkms/vkms_configfs.c | 89 ++++++++++++++++++++++++++++++++++++
2 files changed, 98 insertions(+), 2 deletions(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index dab6811687a2..8383e1b94668 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 6 configurable attributes:
+Planes have 8 configurable attributes:

- type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
exposed by the "type" property of a plane)
@@ -99,9 +99,16 @@ Planes have 6 configurable attributes:
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)
+ by the COLOR_ENCODING property of a plane). If set, supported_color_range
+ must be set too.
- default_color_encoding: Default color encoding presented to the userspace, same
values as supported_color_encoding
+- supported_color_range: Available color range for a plane, as a bitmask:
+ 0x1 DRM_COLOR_YCBCR_LIMITED_RANGE, 0x2 DRM_COLOR_YCBCR_FULL_RANGE (same values as
+ those exposed by the COLOR_RANGE property of a plane). If set, supported_color_encoding
+ must be set too.
+- default_color_range: Default color range presented to the userspace, same
+ values as supported_color_range

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 ee2e8d141f9e..3f658dd41272 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -439,6 +439,91 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
return count;
}

+static ssize_t plane_supported_color_ranges_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int supported_color_range;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ supported_color_range = vkms_config_plane_get_supported_color_ranges(plane->config);
+ }
+
+ return sprintf(page, "%u", supported_color_range);
+}
+
+static ssize_t plane_supported_color_ranges_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_LIMITED_RANGE) |
+ BIT(DRM_COLOR_YCBCR_FULL_RANGE)))
+ return -EINVAL;
+ /* Should at least provide one color range */
+ if ((val & (BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
+ BIT(DRM_COLOR_YCBCR_FULL_RANGE))) == 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_ranges(plane->config, val);
+ }
+
+ return count;
+}
+
+static ssize_t plane_default_color_range_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int default_color_range;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ default_color_range = vkms_config_plane_get_default_color_range(plane->config);
+
+ return sprintf(page, "%u", default_color_range);
+}
+
+static ssize_t plane_default_color_range_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_LIMITED_RANGE) |
+ BIT(DRM_COLOR_YCBCR_FULL_RANGE)))
+ return -EINVAL;
+ /* Should at least provide one color range */
+ if ((val & (BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
+ BIT(DRM_COLOR_YCBCR_FULL_RANGE))) == 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_range(plane->config, val);
+ }
+
+ return count;
+}
+
static ssize_t plane_supported_color_encodings_show(struct config_item *item, char *page)
{
struct vkms_configfs_plane *plane;
@@ -537,6 +622,8 @@ CONFIGFS_ATTR(plane_, type);
CONFIGFS_ATTR(plane_, name);
CONFIGFS_ATTR(plane_, supported_rotations);
CONFIGFS_ATTR(plane_, default_rotation);
+CONFIGFS_ATTR(plane_, supported_color_ranges);
+CONFIGFS_ATTR(plane_, default_color_range);
CONFIGFS_ATTR(plane_, supported_color_encodings);
CONFIGFS_ATTR(plane_, default_color_encoding);

@@ -545,6 +632,8 @@ static struct configfs_attribute *plane_item_attrs[] = {
&plane_attr_name,
&plane_attr_supported_rotations,
&plane_attr_default_rotation,
+ &plane_attr_supported_color_ranges,
+ &plane_attr_default_color_range,
&plane_attr_supported_color_encodings,
&plane_attr_default_color_encoding,
NULL,

--
2.51.0