[PATCH xserver] xfree86: fix gamma compute when palette_size > 256

[Michel Dänzer]

On 30/10/17 11:58 AM, Yu, Qiang wrote:
> If config like this:
> Section "Screen"
>        Identifier      "Screen0"
>        Device          "Card0"
>        DefaultDepth    30
>        DefaultFbBpp    32
> EndSection
> 
> The randr crtc gamma size will be 1024 and this palette_size is also 1024.
> This makes amdgpu-pro 30bit support has wrong gamma setting.
> 
> Or maybe it's better to enlarge the crtc gamma size according to randr crtc
> and let kernel driver to do the resize fit.

Yes, that needs to happen anyway to make the display hardware actually
take advantage of 30 bits per pixel, doesn't it?


> But I see driver like amdgpu with old KMS driver only has 256 entries and the
> gamma set syscall won't work correctly for size>256.

That needs to be fixed then, and the userspace driver should probably
only allow setting depth 30 when it knows the kernel driver can handle it.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer