mgag200 broken on kernel-6.0-rc3 on DELL/T620

[Wang Yugui]

Hi,

> Hi
> 
> Am 14.09.22 um 16:58 schrieb Wang Yugui:
> [...]
> >> 24-bit works on my G200HE and G200 test machines. Maybe the G200ER has a bug.
> >>
> >> When I try 16-bit depth, the display works, but is way too dark. No fiddling with the LUT tables fixes this. It's 90s hardware, so it should support 16-bit framebuffers well, but there's no obvious bug to be seen.
> >>
> >> I guess, we could remove 16 and 24 bit support for now if nothing else helps.
> >
> >
> > maybe better if we revert 73f54d5d9682 (drm/mgag200: Remove special case
> > for G200SE with <2 MiB)
> 
> Could you please test the attached patch on the 6.0-rc3 kernel? It should force the driver to a correct color format if no kernel parameters are given.
> 

This patch works well.

test case detail:
  kernel parm video is not given
  server DELL/T620
  kernel is 6.0-rc5

Best Regards
Wang Yugui (wangyugui at e16-tech.com)
2022/09/15


> Best regards
> Thomas
> 
> >
> > because there is no test result on device G200_SE
> >
> > static unsigned int mgag200_preferred_depth(struct mga_device *mdev)
> > {
> >         if (IS_G200_SE(mdev) && mdev->vram_fb_available < (2048*1024))
> >                 return 16;
> >         else
> >                 return 32;
> > }
> >
> > Best Regards
> > Wang Yugui (wangyugui at e16-tech.com)
> > 2022/09/14
> > 
> -- Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
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