On Fri, Mar 29, 2019 at 10:20:27AM +0100, Daniel Vetter wrote:
> Interpreting it as a 0.16 fixed point means we can't accurately
> represent 1.0. Which is one of the values we really should be able to
> represent.
>
> Since most (all?) luts have lower precision this will only affect
> rounding of 0xffff.
>
> Cc: Uma Shankar <[email protected]>
> Cc: Ville Syrjälä <[email protected]>
> Cc: Shashank Sharma <[email protected]>
> Cc: "Kumar, Kiran S" <[email protected]>
> Cc: Kausal Malladi <[email protected]>
> Cc: Lionel Landwerlin <[email protected]>
> Cc: Matt Roper <[email protected]>
> Cc: Rob Bradford <[email protected]>
> Cc: Daniel Stone <[email protected]>
> Cc: Stefan Schake <[email protected]>
> Cc: Eric Anholt <[email protected]>
> Cc: Maarten Lankhorst <[email protected]>
> Cc: Harry Wentland <[email protected]>
> Cc: Leo Li <[email protected]>
> Cc: [email protected]
> Cc: James (Qian) Wang <[email protected]>
> Cc: Liviu Dudau <[email protected]>
> Cc: Mali DP Maintainers <[email protected]>
> Cc: CK Hu <[email protected]>
> Cc: Philipp Zabel <[email protected]>
> Cc: Yannick Fertre <[email protected]>
> Cc: Philippe Cornu <[email protected]>
> Cc: Benjamin Gaignard <[email protected]>
> Cc: Vincent Abriou <[email protected]>
> Cc: Tomi Valkeinen <[email protected]>
> Cc: Boris Brezillon <[email protected]>
> Signed-off-by: Daniel Vetter <[email protected]>Signed-off-by: Daniel
> Vetter <[email protected]>
Applied, thanks for all the reviews.
-Daniel
> ---
> include/uapi/drm/drm_mode.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index 09d72966899a..83cd1636b9be 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -621,7 +621,8 @@ struct drm_color_ctm {
>
> struct drm_color_lut {
> /*
> - * Data is U0.16 fixed point format.
> + * Values are mapped linearly to 0.0 - 1.0 range, with 0x0 == 0.0 and
> + * 0xffff == 1.0.
> */
> __u16 red;
> __u16 green;
> --
> 2.20.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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