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

[Yu, Qiang]

>> 2. the palette_size can be bigger than crtc->gamma_size, [...]
>
> Can it really? In Aaron's example, both have 1024 entries.
Isn't it 2^11 for palette_size but 2^10 gamma_size?

>> So according to the above understanding, I think there're two solution to the problem:
>> 1. DDX is responsible for setting crtc->gamma_size to max hardware capable gamma
>>     CLUT size, and this patch is still needed for situation like Aaron described (11bit color
>>     but 10bit gamma CLUT) and old amdgpu KMS driver that can only support 256 gamma
>>     CLUT but need 10bit color.
>
> If amdgpu only programs 256 gamma CLUT entries, does the hardware
> actually interpolate the missing entries as described by Aaron?
Need get confirm from DCE and kernel guys.

> Does this allow displaying gradients without banding, whereas the same
> gradients show banding at depth 24?
I don't quite get this question, can you describe in detail?

Regards,
Qiang