[PATCH v3 11/11] drm/vkms: Add driver-specific plane property for testing
From: Maxime Ripard
Date: Tue Sep 08 2026 - 11:34:47 EST
The DRM_MODE_ATOMIC_RESET flag allows userspace to reset all object
states to their defaults before applying new property values. Testing
that this mechanism works correctly requires a property that the test
can set to a non-default value and then verify is properly reset.
Using a standard property for this is problematic: compositors like
Mutter enumerate and track all known properties, making it difficult
to isolate the reset behavior from the compositor's own property
management.
Add a "vkms-test-do-not-use-in-prod" range property to vkms planes.
The property is stored in vkms_plane_state, duplicated across state
copies, and initialized from its registered default in
atomic_create_state via drm_object_property_get_default_value().
Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
---
drivers/gpu/drm/vkms/vkms_drv.h | 3 ++
drivers/gpu/drm/vkms/vkms_plane.c | 61 +++++++++++++++++++++++++++++++++++++--
2 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index dea6cad3f1b9..384616095b45 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -144,20 +144,23 @@ struct conversion_matrix {
* @base: base plane state
* @frame_info: data required for composing computation
* @pixel_read_line: function to read a pixel line in this plane. The creator of a
* struct vkms_plane_state must ensure that this pointer is valid
* @conversion_matrix: matrix used for yuv formats to convert to rgb
+ * @vkms_test_do_not_use_value: driver-specific property for testing only
*/
struct vkms_plane_state {
struct drm_shadow_plane_state base;
struct vkms_frame_info frame_info;
pixel_read_line_t pixel_read_line;
struct conversion_matrix conversion_matrix;
+ unsigned int vkms_test_do_not_use_value;
};
struct vkms_plane {
struct drm_plane base;
+ struct drm_property *vkms_test_do_not_use_property;
};
struct vkms_color_lut {
struct drm_color_lut *base;
size_t lut_length;
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index fd3d34dcf0fe..0ebc131c2788 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -9,14 +9,18 @@
#include <drm/drm_colorop.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_print.h>
+#include <drm/drm_property.h>
#include "vkms_drv.h"
#include "vkms_formats.h"
+#define to_vkms_plane(target) \
+ container_of_const(target, struct vkms_plane, base)
+
static const u32 vkms_formats[] = {
DRM_FORMAT_ARGB8888,
DRM_FORMAT_ABGR8888,
DRM_FORMAT_BGRA8888,
DRM_FORMAT_RGBA8888,
@@ -52,16 +56,19 @@ static const u32 vkms_formats[] = {
};
static struct drm_plane_state *
vkms_plane_duplicate_state(struct drm_plane *plane)
{
+ struct vkms_plane_state *old_state = to_vkms_plane_state(plane->state);
struct vkms_plane_state *vkms_state;
vkms_state = kzalloc_obj(*vkms_state);
if (!vkms_state)
return NULL;
+ vkms_state->vkms_test_do_not_use_value = old_state->vkms_test_do_not_use_value;
+
__drm_gem_duplicate_shadow_plane_state(plane, &vkms_state->base);
return &vkms_state->base.base;
}
@@ -83,28 +90,69 @@ static void vkms_plane_destroy_state(struct drm_plane *plane,
kfree(vkms_state);
}
static struct drm_plane_state *vkms_plane_create_state(struct drm_plane *plane)
{
+ struct vkms_plane *vkms_plane = to_vkms_plane(plane);
struct vkms_plane_state *vkms_state;
+ u64 val;
vkms_state = kzalloc_obj(*vkms_state);
if (!vkms_state) {
DRM_ERROR("Cannot allocate vkms_plane_state\n");
return ERR_PTR(-ENOMEM);
}
__drm_gem_shadow_plane_state_init(plane, &vkms_state->base);
+ if (!drm_object_property_get_default_value(&plane->base,
+ vkms_plane->vkms_test_do_not_use_property,
+ &val))
+ vkms_state->vkms_test_do_not_use_value = val;
+
return &(&vkms_state->base)->base;
}
+static int vkms_plane_atomic_set_property(struct drm_plane *plane,
+ struct drm_plane_state *state,
+ struct drm_property *property,
+ uint64_t val)
+{
+ struct vkms_plane *vkms_plane = to_vkms_plane(plane);
+ struct vkms_plane_state *vkms_state = to_vkms_plane_state(state);
+
+ if (property == vkms_plane->vkms_test_do_not_use_property) {
+ vkms_state->vkms_test_do_not_use_value = val;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static int vkms_plane_atomic_get_property(struct drm_plane *plane,
+ const struct drm_plane_state *state,
+ struct drm_property *property,
+ uint64_t *val)
+{
+ const struct vkms_plane_state *vkms_state = to_vkms_plane_state(state);
+ const struct vkms_plane *vkms_plane = to_vkms_plane(plane);
+
+ if (property == vkms_plane->vkms_test_do_not_use_property) {
+ *val = vkms_state->vkms_test_do_not_use_value;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
static const struct drm_plane_funcs vkms_plane_funcs = {
.update_plane = drm_atomic_helper_update_plane,
.disable_plane = drm_atomic_helper_disable_plane,
- .atomic_create_state = vkms_plane_create_state,
- .atomic_duplicate_state = vkms_plane_duplicate_state,
+ .atomic_set_property = vkms_plane_atomic_set_property,
+ .atomic_get_property = vkms_plane_atomic_get_property,
+ .atomic_create_state = vkms_plane_create_state,
+ .atomic_duplicate_state = vkms_plane_duplicate_state,
.atomic_destroy_state = vkms_plane_destroy_state,
};
static void vkms_plane_atomic_update(struct drm_plane *plane,
struct drm_atomic_commit *state)
@@ -281,10 +329,19 @@ struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
BIT(DRM_COLOR_YCBCR_FULL_RANGE),
DRM_COLOR_YCBCR_BT601,
DRM_COLOR_YCBCR_FULL_RANGE);
+ plane->vkms_test_do_not_use_property =
+ drm_property_create_range(dev, 0,
+ "vkms-test-do-not-use-in-prod",
+ 0, U32_MAX);
+ if (plane->vkms_test_do_not_use_property)
+ drm_object_attach_property(&plane->base.base,
+ plane->vkms_test_do_not_use_property,
+ 0);
+
if (vkms_config_plane_get_default_pipeline(plane_cfg))
vkms_initialize_colorops(&plane->base);
return plane;
}
--
2.55.0