> > > So no tests that actually verify that the kernel properly rejects
> > > stuff stuff like modesets, gamma LUT updates, plane movement,
> > > etc.?
> >
> > Pondering this a bit more, it just occurred to me the current driver
> > level checks might easily lead to confusing behaviour. Eg. is
> > the ioctl going to succeed if you ask for an async change of some
> > random property while the crtc disabled, but fails if you ask for
> > the same async property change when the crtc is active?
> >
> > So another reason why rejecting most properties already at
> > the uapi level might be a good idea.
>
> And just to be clear this is pretty much what I suggest:
>
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index 79730fa1dd8e..471a2c703847 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -1392,6 +1392,13 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
> goto out;
> }
>
> + if (arg->flags & DRM_MODE_PAGE_FLIP_ASYNC &&
> + prop != dev->mode_config.prop_fb_id) {
> + drm_mode_object_put(obj);
> + ret = -EINVAL;
> + goto out;
> + }
> +
> if (copy_from_user(&prop_value,
> prop_values_ptr + copied_props,
> sizeof(prop_value))) {
>
>
> That would actively discourage people from even attempting the
> "just dump all the state into the ioctl" approach with async flips
> since even the props whose value isn't even changing would be rejected.
How does this sound?
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 945761968428..ffd16bdc7b83 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -972,14 +972,26 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
struct drm_file *file_priv,
struct drm_mode_object *obj,
struct drm_property *prop,
- uint64_t prop_value)
+ uint64_t prop_value,
+ bool async_flip)
{
struct drm_mode_object *ref;
int ret;
+ uint64_t old_val;
if (!drm_property_change_valid_get(prop, prop_value, &ref))
return -EINVAL;
+ if (async_flip && prop != prop->dev->mode_config.prop_fb_id) {
+ ret = drm_atomic_get_property(obj, prop, &old_val);
+ if (ret != 0 || old_val != prop_value) {
+ drm_dbg_atomic(prop->dev,
+ "[PROP:%d:%s] cannot be changed during async flip\n",
+ prop->base.id, prop->name);
+ return -EINVAL;
+ }
+ }
+
switch (obj->type) {
case DRM_MODE_OBJECT_CONNECTOR: {
struct drm_connector *connector = obj_to_connector(obj);
