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

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

(cc: Jocelyn)

Hi

Am 14.09.22 um 10:29 schrieb Wang Yugui:
> Hi,
>
>
> > Hi
> >
> > Am 13.09.22 um 17:15 schrieb Wang Yugui:
> > [...]
> > > > > so I tried to revert patch of mgag200 driver in batch of 2 or 3, the I
> > > > > noticed the patch 'Subject: drm/mgag200: Remove special case for G200SE
> > > > > with <2 MiB' and then tried this dirty fix.
> > > >
> > > > Oh, great work! Thank you. From looking at the screenshot that you provided, it seems as if the 24-bit mode setting is broken. I'm not sure why the G200SE workaround applies to a G200ER, but we'll see.
> > >
> > > I tested 'preferred_depth = 32' too. it works on T630 too.
> > >
> > > so both 16 and 32 work, but 24 failed on DELL/T630.
> >
> > I tried on my test machine with a 5.19 kernel and found that 32-bit and 24-bit pixels work, but 16-bit looks incorrect.
> >
> > What are the results if you boot your kernel 5.19.3 with the parameter video=1024x768-24? This should enable 24-bit pixels.
> >
> > How does video=1024x768-16 look with the 5.19 kernel?
>
> test result here
> kernel 5.19.3 & video=1024x768-24
> 	dell/T620/centos-8.5	broken
> 	dell/T630/centos-7.9	broken

I assume that Centos 7 and 8 have fairly old kernels? So it's been a 
long-standing bug.

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.

Best regards
Thomas

> kernel 5.19.3 & video=1024x768-32
> 	dell/T620/centos-8.5	OK
> 	dell/T630/centos-7.9	OK



> Both DELL/T620 and DELL/T630 have the lastest BIOS/iDRAC installed.
>
> Best Regards
> Wang Yugui (wangyugui@xxxxxxxxxxxx)
> 2022/09/14
>
>
>
> > Best regards
> > Thomas
> >
> > > diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > b/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > index 225cca2ed60e..563e3ab05fbc 100644
> > > --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > @@ -1070,7 +1070,7 @@ int mgag200_modeset_init(struct mga_device *mdev, resource_size_t vram_available
> > >
> > >           dev->mode_config.max_width = MGAG200_MAX_FB_WIDTH;
> > >           dev->mode_config.max_height = MGAG200_MAX_FB_HEIGHT;
> > > -       dev->mode_config.preferred_depth = 24;
> > > +       dev->mode_config.preferred_depth = 32;
> > >           dev->mode_config.fb_base = mdev->vram_res->start;
> > >           dev->mode_config.funcs = &mgag200_mode_config_funcs;
> > >
> > > Best Regards
> > > Wang Yugui (wangyugui@xxxxxxxxxxxx)
> > > 2022/09/13
> > -- Thomas Zimmermann
> > Graphics Driver Developer
> > SUSE Software Solutions Germany GmbH
> > Maxfeldstr. 5, 90409 Nürnberg, Germany
> > (HRB 36809, AG Nürnberg)
> > Gesch?ftsführer: Ivo Totev

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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