On Tue, Jan 31, 2017 at 05:43:48PM +, Brian Starkey wrote:
> Explicitly state the expected CTM equations in the kerneldoc for the CTM
> property, and the form of the matrix on struct drm_color_ctm.
>
> Cc: Ville Syrjälä
> Cc: Lionel Landwerlin
> Cc: Daniel Vetter
> Signed-off-by: Brian Starkey
Ugh, but well that's the current uabi. Applied to drm-misc-next, thanks
for your patch. One idea below.
> ---
> drivers/gpu/drm/drm_color_mgmt.c | 13 +
> include/uapi/drm/drm_mode.h | 14 +-
> 2 files changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c
> b/drivers/gpu/drm/drm_color_mgmt.c
> index 789b4c65cd69..307f7b0545b6 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -62,6 +62,19 @@
> * unit/pass-thru matrix should be used. This is generally the driver
> * boot-up state too.
> *
> + * The output vector is related to the input vector as below::
> + *
> + * 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];
> + *
> + * The component order in the input/output vectors is assumed to be
> + * { R, G, B }.
> + *
> + * The color-space of the input vector must not be confused with the
> + * color-space implied by a framebuffer pixel format, which may be the same
> + * or different.
> + *
> * “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
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index ce7efe2e8a5e..3f179b8867e5 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -525,7 +525,19 @@ struct drm_mode_crtc_lut {
> };
>
> struct drm_color_ctm {
> - /* Conversion matrix in S31.32 format. */
> + /*
> + * Conversion matrix in row-major form:
> + *
> + * | matrix[0] matrix[1] matrix[2] |
> + * | matrix[3] matrix[4] matrix[5] |
> + * | matrix[6] matrix[7] matrix[8] |
> + *
> + * Each element is in a sign + magnitude format: S31.32, with the sign
> + * in bit 63, and the magnitude represented as fixed-point 31.32.
> + *
> + * i.e. +1.25 = 0x0001.4000
> + * -1.25 = 0x8001.4000
> + */
This is great, except none of our uabi headers are part of the kernel-doc
build :( If you have time, would be real awesome to include them, and at
least give this struct here a proper kernel-doc. Then you could also
reference it in the above kerneldoc comment in drm_color_mgmt.c.
We already have a drm-uapi.rst file, adding a new section there for
userspace abi headers seems like the right place for the include stanza.
Cheers, Daniel
> __s64 matrix[9];
> };
>
> --
> 1.7.9.5
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
