[PATCH v6 4/5] Documentation: add doc for sync_file_get_fence()

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

Document the new function added to sync_file.c

v2: Adapt to fence_array

v3: Take in Chris Wilson suggestions

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Acked-by: Christian KÃnig <christian.koenig@xxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
 Documentation/sync_file.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/sync_file.txt b/Documentation/sync_file.txt
index e8e2eba..b63a685 100644
--- a/Documentation/sync_file.txt
+++ b/Documentation/sync_file.txt
@@ -64,6 +64,20 @@ The sync_file fd now can be sent to userspace.
 If the creation process fail, or the sync_file needs to be released by any
 other reason fput(sync_file->file) should be used.
 
+Receiving Sync Files from Userspace
+-----------------------------------
+
+When userspace needs to send an in-fence to the driver it passes file descriptor
+of the Sync File to the kernel. The kernel can then retrieve the fences
+from it.
+
+Interface:
+	struct fence *sync_file_get_fence(int fd);
+
+
+The returned reference is owned by the caller and must be disposed of
+afterwards using fence_put(). In case of error, a NULL is returned instead.
+
 References:
 [1] struct sync_file in include/linux/sync_file.h
 [2] All interfaces mentioned above defined in include/linux/sync_file.h
-- 
2.5.5