To allows the userspace to test many hardware configurations, introduce a
new interface to configure the available rotation per planes. VKMS
supports any rotation and reflection, so the userspace can choose any
combination.

The supported rotations are configured by writing a rotation bitmask to
the file `supported_rotations` and the default rotation is chosen by
writing a rotation bitmask to `default_rotation`.

Signed-off-by: Louis Chauvet <[email protected]>
---
 Documentation/ABI/testing/configfs-vkms | 15 ++++++
 Documentation/gpu/vkms.rst              |  7 ++-
 drivers/gpu/drm/vkms/vkms_configfs.c    | 93 ++++++++++++++++++++++++++++++---
 3 files changed, 108 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/configfs-vkms 
b/Documentation/ABI/testing/configfs-vkms
index 6fe375d1636f..9b74375bbf35 100644
--- a/Documentation/ABI/testing/configfs-vkms
+++ b/Documentation/ABI/testing/configfs-vkms
@@ -109,6 +109,21 @@ Contact:   [email protected]
 Description:
         Name of the plane.
 
+What:          
/sys/kernel/config/vkms/<device>/planes/<plane>/possible_rotations
+Date:          Nov 2025
+Contact:       [email protected]
+Description:
+        Available rotations for the plane, as a bitmask:
+        0x01 - no rotation, 0x02 - rotate 90°, 0x04 - rotate 180°,
+        0x08 - rotate 270°, 0x10 - reflect x, 0x20 - reflect y.
+
+What:          /sys/kernel/config/vkms/<device>/planes/<plane>/default_rotation
+Date:          Nov 2025
+Contact:       [email protected]
+Description:
+        Default rotation presented to userspace, same values as
+        possible_rotations.
+
 What:          /sys/kernel/config/vkms/<device>/planes/<plane>/possible_crtcs
 Date:          Nov 2025
 Contact:       [email protected]
diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index 79f1185d8645..7fd746dd6ee2 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -87,11 +87,16 @@ Start by creating one or more planes::
 
   sudo mkdir /config/vkms/my-vkms/planes/plane0
 
-Planes have 2 configurable attributes:
+Planes have 4 configurable attributes:
 
 - type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
   exposed by the "type" property of a plane)
 - name: Name of the plane. Allowed characters are [A-Za-z1-9_-]
+- possible_rotations: Available rotation for a plane, as a bitmask: 0x01 no 
rotation,
+  0x02 rotate 90°, 0x04 rotate 180°, 0x08 rotate 270°, 0x10 reflect x, 0x20 
reflect y
+  (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.
 
 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 989788042191..bcc3e222e6b3 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -365,24 +365,105 @@ static ssize_t plane_name_store(struct config_item 
*item, const char *page,
        return (ssize_t)count;
 }
 
+static ssize_t plane_supported_rotations_show(struct config_item *item, char 
*page)
+{
+       struct vkms_configfs_plane *plane;
+       unsigned int plane_supported_rotations;
+
+       plane = plane_item_to_vkms_configfs_plane(item);
+
+       scoped_guard(mutex, &plane->dev->lock) {
+               plane_supported_rotations = 
vkms_config_plane_get_supported_rotations(plane->config);
+       }
+
+       return sprintf(page, "%u", plane_supported_rotations);
+}
+
+static ssize_t plane_supported_rotations_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, 0, &val);
+       if (ret)
+               return ret;
+
+       /* Should be a supported value */
+       if (val & ~(DRM_MODE_ROTATE_MASK | DRM_MODE_REFLECT_MASK))
+               return -EINVAL;
+       /* Should at least provide one rotation */
+       if (!(val & DRM_MODE_ROTATE_MASK))
+               return -EINVAL;
+
+       scoped_guard(mutex, &plane->dev->lock) {
+               if (plane->dev->enabled)
+                       return -EBUSY;
+
+               vkms_config_plane_set_supported_rotations(plane->config, val);
+       }
+
+       return count;
+}
+
+static ssize_t plane_default_rotation_show(struct config_item *item, char 
*page)
+{
+       struct vkms_configfs_plane *plane = 
plane_item_to_vkms_configfs_plane(item);
+       unsigned int plane_default_rotation;
+
+       scoped_guard(mutex, &plane->dev->lock) {
+               plane_default_rotation = 
vkms_config_plane_get_default_rotation(plane->config);
+       }
+
+       return sprintf(page, "%u", plane_default_rotation);
+}
+
+static ssize_t plane_default_rotation_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 & ~(DRM_MODE_ROTATE_MASK | DRM_MODE_REFLECT_MASK))
+               return -EINVAL;
+
+       /* Should contain exactly one rotation */
+       if (!is_power_of_2(val & DRM_MODE_ROTATE_MASK))
+               return -EINVAL;
+
+       scoped_guard(mutex, &plane->dev->lock) {
+               if (plane->dev->enabled)
+                       return -EBUSY;
+
+               vkms_config_plane_set_default_rotation(plane->config, val);
+       }
+
+       return count;
+}
+
 CONFIGFS_ATTR(plane_, type);
 CONFIGFS_ATTR(plane_, name);
+CONFIGFS_ATTR(plane_, supported_rotations);
+CONFIGFS_ATTR(plane_, default_rotation);
 
 static struct configfs_attribute *plane_item_attrs[] = {
        &plane_attr_type,
        &plane_attr_name,
+       &plane_attr_supported_rotations,
+       &plane_attr_default_rotation,
        NULL,
 };
 
 static void plane_release(struct config_item *item)
 {
-       struct vkms_configfs_plane *plane;
-       struct mutex *lock;
-
-       plane = plane_item_to_vkms_configfs_plane(item);
-       lock = &plane->dev->lock;
+       struct vkms_configfs_plane *plane = 
plane_item_to_vkms_configfs_plane(item);
 
-       scoped_guard(mutex, lock) {
+       scoped_guard(mutex, &plane->dev->lock) {
                vkms_config_destroy_plane(plane->config);
                kfree(plane);
        }

-- 
2.51.2

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