On 3/29/19 10:20 AM, 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 uma.shankar@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Shashank Sharma shashank.sharma@intel.com Cc: "Kumar, Kiran S" kiran.s.kumar@intel.com Cc: Kausal Malladi kausalmalladi@gmail.com Cc: Lionel Landwerlin lionel.g.landwerlin@intel.com Cc: Matt Roper matthew.d.roper@intel.com Cc: Rob Bradford robert.bradford@intel.com Cc: Daniel Stone daniels@collabora.com Cc: Stefan Schake stschake@gmail.com Cc: Eric Anholt eric@anholt.net Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Harry Wentland harry.wentland@amd.com Cc: Leo Li sunpeng.li@amd.com Cc: amd-gfx@lists.freedesktop.org Cc: James (Qian) Wang james.qian.wang@arm.com Cc: Liviu Dudau liviu.dudau@arm.com Cc: Mali DP Maintainers malidp@foss.arm.com Cc: CK Hu ck.hu@mediatek.com Cc: Philipp Zabel p.zabel@pengutronix.de Cc: Yannick Fertre yannick.fertre@st.com Cc: Philippe Cornu philippe.cornu@st.com Cc: Benjamin Gaignard benjamin.gaignard@linaro.org Cc: Vincent Abriou vincent.abriou@st.com Cc: Tomi Valkeinen tomi.valkeinen@ti.com Cc: Boris Brezillon bbrezillon@kernel.org Signed-off-by: Daniel Vetter daniel.vetter@ffwll.chSigned-off-by: Daniel Vetter daniel.vetter@intel.com
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.
for stm, Reviewed-by: Philippe Cornu philippe.cornu@st.com Many thanks Philippe :-)
*/__u16 red; __u16 green;