[PATCH 4/4] drm/doc: document front-buffer rendering

[Simon Ser]

Explain how to perform front-buffer rendering.

Signed-off-by: Simon Ser <contact at emersion.fr>
Cc: Pekka Paalanen <pekka.paalanen at collabora.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/drm_blend.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 6e74de833466..6c55f1da2480 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -75,6 +75,9 @@
  * 	the currently visible vertical area of the &drm_crtc.
  * FB_ID:
  * 	Mode object ID of the &drm_framebuffer this plane should scan out.
+ *
+ * 	To perform front-buffer rendering, user-space should set FB_ID to the
+ * 	previous framebuffer in atomic commits.
  * CRTC_ID:
  * 	Mode object ID of the &drm_crtc this plane should be connected to.
  *
-- 
2.41.0