[PATCH] drm/color: Include CTM equations in kerneldoc

[Brian Starkey]

Explicitly state the expected CTM equations in the kerneldoc for the CTM
property.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Brian Starkey <brian.starkey at arm.com>
---

Hi,

This captures the outcome of the discussion on #dri-devel yesterday
(2017-01-26):
https://people.freedesktop.org/~cbrill/dri-log/?channel=dri-devel&date=2017-01-26

I'm not sure about the stance on such explicit rst markup in kerneldoc,
but without it the equations are pretty unreadable in the rendered
output.

Cheers,
Brian

 drivers/gpu/drm/drm_color_mgmt.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 789b4c65cd69..63f3a7404fa1 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -62,6 +62,16 @@
  *	unit/pass-thru matrix should be used. This is generally the driver
  *	boot-up state too.
  *
+ *	Given an input vector ``in[3]`` and an output vector ``out[3]``, the
+ *	transformation applied is:
+ *
+ *	| ``out[0] = matrix[0] * in[0] + matrix[1] * in[1] + matrix[2] * in[2];``
+ *	| ``out[1] = matrix[3] * in[0] + matrix[4] * in[1] + matrix[5] * in[2];``
+ *	| ``out[2] = matrix[6] * in[0] + matrix[7] * in[1] + matrix[8] * in[2];``
+ *
+ *	| For RGB formats, the input vector is assumed to be ``{ R, G, B }``.
+ *	| For YCbCr formats, the input vector is assumed to be ``{ Y, Cb, Cr }``.
+ *
  * “GAMMA_LUT”:
  *	Blob property to set the gamma lookup table (LUT) mapping pixel data
  *	after the transformation matrix to data sent to the connector. The
-- 
1.7.9.5