drm: Clarify DRM_MODE_REFLECT_X/Y documentation

DRM_MODE_REFLECT_X and DRM_MODE_REFLECT_Y meaning seems a bit unclear
to me, so try to clarify that with a bit of ascii graphics.

Changes since v1:
  - Move the ascii graphics in the kerneldoc where all plane
    properties are already documented and make sure it's properly
    rendered, suggestested by Daniel Vetter.

Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180910172946.18539-1-alexandru-cosmin.gheorghe@arm.com

diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 402b62d3f07208ccfc61009ef9fe6023c2702652..0c78ca386cbe89ba1451d0fef62a6057f610b6df 100644 (file)
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -101,6 +101,28 @@
  *     Without this property the rectangle is only scaled, but not rotated or
  *     reflected.
  *
+ *     Possbile values:
+ *
+ *     "rotate-<degrees>":
+ *             Signals that a drm plane is rotated <degrees> degrees in counter
+ *             clockwise direction.
+ *
+ *     "reflect-<axis>":
+ *             Signals that the contents of a drm plane is reflected along the
+ *             <axis> axis, in the same way as mirroring.
+ *
+ *     reflect-x::
+ *
+ *                     |o |    | o|
+ *                     |  | -> |  |
+ *                     | v|    |v |
+ *
+ *     reflect-y::
+ *
+ *                     |o |    | ^|
+ *                     |  | -> |  |
+ *                     | v|    |o |
+ *
  * zpos:
  *     Z position is set up with drm_plane_create_zpos_immutable_property() and
  *     drm_plane_create_zpos_property(). It controls the visibility of overlapping

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 8d67243952f4f104f8b2ca745b4d94aa2565cbcc..d3e0fe31efc55351573be5432ca92d3c372b1c08 100644 (file)
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -186,8 +186,9 @@ extern "C" {
 /*
  * DRM_MODE_REFLECT_<axis>
  *
- * Signals that the contents of a drm plane is reflected in the <axis> axis,
+ * Signals that the contents of a drm plane is reflected along the <axis> axis,
  * in the same way as mirroring.
+ * See kerneldoc chapter "Plane Composition Properties" for more details.
  *
  * This define is provided as a convenience, looking up the property id
  * using the name->prop id lookup is the preferred method.