Modern compositor rely on zpos management to offload some processing to
deticated hardware. In order to test multiple configurations, add zpos
configuration to configFS.
Introduce multiple attributes to configure zpos:
- zpos_enabled - Create or not the zpos property. If not created, the zpos
is undefined.
- zpos_mutable - If the zpos property is created, allow or not the
userspace to modify it
- zpos_initial - Initial value for zpos property. Must be between zpos_min
and zpos_max
- zpos_min - Minimum zpos value for this plane. Must be <= zpos_max
- zpos_max - Maximum zpos value for this plane. Must be >= zpos_min
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Documentation/ABI/testing/configfs-vkms | 36 +++++++
Documentation/gpu/vkms.rst | 9 +-
drivers/gpu/drm/vkms/vkms_configfs.c | 180 ++++++++++++++++++++++++++++++++
3 files changed, 224 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/configfs-vkms b/Documentation/ABI/testing/configfs-vkms
index 48f92538c602..34cb6aeec411 100644
--- a/Documentation/ABI/testing/configfs-vkms
+++ b/Documentation/ABI/testing/configfs-vkms
@@ -162,6 +162,42 @@ Description:
use '-' prefix. Use '+*' to add all formats, '-*' to
remove all.
+What: /sys/kernel/config/vkms/<device>/planes/<plane>/zpos_enabled
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Enable or disable the zpos property. Value: 1 - enabled,
+ 0 - disabled.
+
+What: /sys/kernel/config/vkms/<device>/planes/<plane>/zpos_mutable
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Create the zpos property as mutable or immutable.
+ Value: 1 - mutable, 0 - immutable. No effect if
+ zpos_enabled is not set.
+
+What: /sys/kernel/config/vkms/<device>/planes/<plane>/zpos_initial
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Set the initial zpos value. Must be between zpos_min
+ and zpos_max. No effect if zpos_enabled is not set.
+
+What: /sys/kernel/config/vkms/<device>/planes/<plane>/zpos_min
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Set the minimal zpos value. No effect if zpos_enabled
+ is not set.
+
+What: /sys/kernel/config/vkms/<device>/planes/<plane>/zpos_max
+Date: Nov 2025
+Contact: dri-devel@lists.freedesktop.org
+Description:
+ Set the maximal zpos value. No effect if zpos_enabled
+ is not set.
+
What: /sys/kernel/config/vkms/<device>/planes/<plane>/possible_crtcs
Date: Nov 2025
Contact: dri-devel@lists.freedesktop.org
diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index 15d62ad963c9..791c4f33a90a 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 9 configurable attributes:
+Planes have 14 configurable attributes:
- type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
exposed by the "type" property of a plane)
@@ -114,6 +114,13 @@ Planes have 9 configurable attributes:
To remove a format, use a minus and its fourcc: -XR24
To add all formats use +*
To remove all formats, use -*
+- zpos_enabled: Enable or not the zpos property: 1 enable, 0 disable
+- zpos_mutable: Create the zpos property as a mutable or imutable property: 1 mutable,
+ 0 immutable. No effect if zpos_enabled is not set.
+- zpos_initial: Set the initial zpos value. Must be between zpos_min and zpos_max. No
+ effect if zpos_enabled is not set.
+- zpos_min: Set the minimum zpos value. No effect if zpos_enabled is not set.
+- zpos_max: Set the maximum zpos value. No effect if zpos_enabled is not set.
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 a451d1122acf..e7f3ab54b5a1 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -744,6 +744,176 @@ static ssize_t plane_supported_formats_store(struct config_item *item,
return count;
}
+static ssize_t plane_zpos_enabled_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ bool enabled;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ enabled = vkms_config_plane_get_zpos_enabled(plane->config);
+
+ return sprintf(page, "%d\n", enabled);
+}
+
+static ssize_t plane_zpos_enabled_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_plane *plane;
+ bool enabled;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ if (kstrtobool(page, &enabled))
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ if (plane->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_plane_set_zpos_enabled(plane->config, enabled);
+ }
+
+ return (ssize_t)count;
+}
+
+static ssize_t plane_zpos_mutable_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ bool mutable;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ mutable = vkms_config_plane_get_zpos_mutable(plane->config);
+
+ return sprintf(page, "%d\n", mutable);
+}
+
+static ssize_t plane_zpos_mutable_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_plane *plane;
+ bool mutable;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ if (kstrtobool(page, &mutable))
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ if (plane->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_plane_set_zpos_mutable(plane->config, mutable);
+ }
+
+ return (ssize_t)count;
+}
+
+static ssize_t plane_zpos_initial_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int initial;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ initial = vkms_config_plane_get_zpos_initial(plane->config);
+
+ return sprintf(page, "%u\n", initial);
+}
+
+static ssize_t plane_zpos_initial_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int initial;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ if (kstrtouint(page, 10, &initial))
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ if (plane->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_plane_set_zpos_initial(plane->config, initial);
+ }
+
+ return (ssize_t)count;
+}
+
+static ssize_t plane_zpos_min_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int min;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ min = vkms_config_plane_get_zpos_min(plane->config);
+
+ return sprintf(page, "%u\n", min);
+}
+
+static ssize_t plane_zpos_min_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int min;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ if (kstrtouint(page, 10, &min))
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ if (plane->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_plane_set_zpos_min(plane->config, min);
+ }
+
+ return (ssize_t)count;
+}
+
+static ssize_t plane_zpos_max_show(struct config_item *item, char *page)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int max;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ scoped_guard(mutex, &plane->dev->lock)
+ max = vkms_config_plane_get_zpos_max(plane->config);
+
+ return sprintf(page, "%u\n", max);
+}
+
+static ssize_t plane_zpos_max_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct vkms_configfs_plane *plane;
+ unsigned int max;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+
+ if (kstrtouint(page, 10, &max))
+ return -EINVAL;
+
+ scoped_guard(mutex, &plane->dev->lock) {
+ if (plane->dev->enabled)
+ return -EBUSY;
+
+ vkms_config_plane_set_zpos_max(plane->config, max);
+ }
+
+ return (ssize_t)count;
+}
+
CONFIGFS_ATTR(plane_, type);
CONFIGFS_ATTR(plane_, name);
CONFIGFS_ATTR(plane_, supported_rotations);
@@ -753,6 +923,11 @@ CONFIGFS_ATTR(plane_, default_color_range);
CONFIGFS_ATTR(plane_, supported_color_encodings);
CONFIGFS_ATTR(plane_, default_color_encoding);
CONFIGFS_ATTR(plane_, supported_formats);
+CONFIGFS_ATTR(plane_, zpos_enabled);
+CONFIGFS_ATTR(plane_, zpos_mutable);
+CONFIGFS_ATTR(plane_, zpos_initial);
+CONFIGFS_ATTR(plane_, zpos_min);
+CONFIGFS_ATTR(plane_, zpos_max);
static struct configfs_attribute *plane_item_attrs[] = {
&plane_attr_type,
@@ -764,6 +939,11 @@ static struct configfs_attribute *plane_item_attrs[] = {
&plane_attr_supported_color_encodings,
&plane_attr_default_color_encoding,
&plane_attr_supported_formats,
+ &plane_attr_zpos_enabled,
+ &plane_attr_zpos_mutable,
+ &plane_attr_zpos_initial,
+ &plane_attr_zpos_min,
+ &plane_attr_zpos_max,
NULL,
};
--
2.51.2