Hi Ville,

On Thu, Feb 22, 2018 at 11:42:29PM +0200, Ville Syrjala wrote:
From: Ville Syrjälä <ville.syrj...@linux.intel.com>

The documentation for the ctm matrix suggests a two's complement
format, but at least the i915 implementation is using sign-magnitude
instead. And looks like malidp is doing the same. Change the docs
to match the current implementation, and change the type from __s64
to __u64 to drive the point home.

I totally agree that this is a good idea, but...

Cc: dri-devel@lists.freedesktop.org
Cc: Mihail Atanassov <mihail.atanas...@arm.com>
Cc: Liviu Dudau <liviu.du...@arm.com>
Cc: Brian Starkey <brian.star...@arm.com>
Cc: Mali DP Maintainers <mal...@foss.arm.com>
Cc: Johnson Lin <johnson....@intel.com>
Cc: Uma Shankar <uma.shan...@intel.com>
Cc: Shashank Sharma <shashank.sha...@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
include/uapi/drm/drm_mode.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 2c575794fb52..b5d7d9e0eff5 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -598,8 +598,11 @@ struct drm_mode_crtc_lut {

struct drm_color_ctm {
-       /* Conversion matrix in S31.32 format. */
-       __s64 matrix[9];
+       /*
+        * Conversion matrix in S31.32 sign-magnitude
+        * (not two's complement!) format.
+        */
+       __u64 matrix[9];

Isn't changing the type liable to break something for someone?



struct drm_color_lut {

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