[PATCH] drm: document that blobs are ref'counted

[Simon Ser]

User-space doesn't need to keep track of blobs that might be in use by
the kernel. User-space can just destroy blobs as soon as they don't need
them anymore.

Signed-off-by: Simon Ser <contact at emersion.fr>
Cc: Pekka Paalanen <ppaalanen at gmail.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Jonas Ådahl <jadahl at gmail.com>
---
 include/uapi/drm/drm_mode.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 863eda048265..f7c41aa4b5eb 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -924,6 +924,10 @@ struct drm_mode_create_blob {
  * struct drm_mode_destroy_blob - Destroy user blob
  * @blob_id: blob_id to destroy
  * Destroy a user-created blob property.
+ *
+ * Blobs are reference-counted by the kernel, so user-space can destroy them as
+ * soon as they're done with them.  For instance user-space can destroy a blob
+ * used in an atomic commit right after performing the atomic commit ioctl.
  */
 struct drm_mode_destroy_blob {
 	__u32 blob_id;
-- 
2.28.0