[PATCH] drm/mgag200: Increase bandwidth for G200se A rev1

[Jocelyn Falempe]

On 26/07/2023 12:11, Roger Sewell wrote:
> 
> Jocelyn,
> 
>>> How can I check for sure whether I am using 24 or 32 bits per pixel
>>> ?
>>
>> The easiest solution if you already rebuilt your kernel is to print
>> the variable bpp here:
>>
>> https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/mgag200/mgag200_mode.c#L326
>>
>> pr_info("mgag200 bpp %d\n", bpp);
> 
> Did that, and I get "mgag200 bpp 32".
> 
>> Also if you can run Wayland at 1440x900 at 60, that would mean the
>> hardware is indeed able to handle it in 32bit.
> 
> I can indeed run Wayland at 1440x900 at 60.
> 
> So I think I'm right in saying that my graphics chip can handle
> 1440x900 at 60 with 32 bits per pixel.

Thanks for confirming that. So either the specification is a bit too 
conservative, or your specific hardware is above average.
> 
> However, while searching /var/log/messages for the bpp output above, I
> also found these two lines:
> 
> /usr/libexec/gdm-x-session[2366]: (==) modeset(0): Depth 24, (==) framebuffer bpp 32
> /usr/libexec/gdm-x-session[2366]: (==) modeset(0): RGB weight 888

Yes in 32bits, only 24 are actual color, the remaining 8 bits are 
discarded. In newer monitor, you can have 10 bits per color, but that 
would still be 32bits per pixel. Thus in your case the color depth is 24 
and bits_per_pixel is 32, which is the most common.
> 
> in case it makes a difference.
> 
> Thanks,
> Roger.
>