At screen depths > 24 bit, the color palettes passed into
xf86Randr12CrtcComputeGamma() can have a larger number of slots
than the crtc's hardware lut. E.g., at depth 30, 1024 palette
slots vs. 256 hw lut slots. This palette size > crtc gamma size
case is not handled yet and leads to silent failure, so gamma
table updates do not happen.
Add a new subsampling path for this case.
This makes lut updates work again, as tested with the xgamma
utility (uses XF86VidMode extension) and some RandR based
gamma ramp animation.
v2: Better resampling when subsampling the palette, as
proposed by Ville. Now reaches the max index of the
palette and deals with non-power-of-two sizes. Thanks.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reviewed-by: Antoine Martin <antoine@nagafix.co.uk> (v1)
Cc: <ville.syrjala@linux.intel.com>
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