[016/237] drm/rcar-du: Clarify comment regarding plane Y source coordinate

Commit Message

Simon Horman Dec. 14, 2013, 5:49 a.m. UTC

From: Laurent Pinchart <[e-mail]>

The R8A7790 DU documentation contains further information regarding the
plane Y source coordinate. Update the comment accordingly.

Signed-off-by: Laurent Pinchart <[e-mail]>
(cherry picked from commit 9e7db06d3ac0ffcd866e5b7114f9a7ba12f7b6ac)
Signed-off-by: Simon Horman <[e-mail]>
---
 drivers/gpu/drm/rcar-du/rcar_du_plane.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_plane.c b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
index a65f81d..38ebd20 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
@@ -103,9 +103,12 @@  void rcar_du_plane_update_base(struct rcar_du_plane *plane)
 	struct rcar_du_device *rcdu = plane->dev;
 	unsigned int index = plane->hwindex;
 
-	/* According to the datasheet the Y position is expressed in raster line
-	 * units. However, 32bpp formats seem to require a doubled Y position
-	 * value. Similarly, for the second plane, NV12 and NV21 formats seem to
+	/* The Y position is expressed in raster line units and must be doubled
+	 * for 32bpp formats, according to the R8A7790 datasheet. No mention of
+	 * doubling the Y position is found in the R8A7779 datasheet, but the
+	 * rule seems to apply there as well.
+	 *
+	 * Similarly, for the second plane, NV12 and NV21 formats seem to
 	 * require a halved Y position value.
 	 */
 	rcar_du_plane_write(rcdu, index, PnSPXR, plane->src_x);