[Nouveau] Meaning of MMIO register 100080 on NV28

[Ilia Mirkin]

Ping?

On Thu, May 1, 2014 at 6:26 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Hello,
>
> There have been some users reporting odd framebuffer and cursor
> corruption on GeForce4 Ti 4200 Go cards (yeah, pretty ancient
> hardware). These identify as NV28's.
>
> Here is the full bug, with screenshots, descriptions, etc:
> https://bugs.freedesktop.org/show_bug.cgi?id=54700
>
> A user has isolated bit 24 of 100080 needing to be set, at which point
> all the problems disappear. We don't know very much about this
> register -- we write to it at device init time on NV04/NV05 (Riva
> TNT/TNT2), toggling bit 4 on and off ("REFRESH_OFF"), but not on any
> chips after that.
>
> My main question is this -- when should we be setting bit 24 of
> 100080, and on what chips? If it's easy, a brief description of what
> it means would be great too. And any other advice you may have on this
> issue, as always, would be most welcome.
>
> Thanks,
>
>   -ilia
>
> P.S. Thanks for responding to my other questions as well. Hope I'm not
> becoming too much of a nuisance :)