[RFC] Remove AGP support from Radeon/Nouveau/TTM

[Rui Salvaterra]

On Tue, 12 May 2020 at 08:58, Michel Dänzer <michel at daenzer.net> wrote:
>
> FWIW, on my last-generation PowerBook with RV350 (IIRC), there was a big
> performance difference between AGP and PCI GART. The latter was sort of
> usable for normal desktop operation, but not so much for OpenGL apps
> (which were usable with AGP).

I never really understood what were the issues with AGP on PowerPC
(well, Apple, the only ones I've tested) machines. I mean, did OS X
also disable AGP entirely, or did it have workarounds somewhere else
on the stack nobody was able to figure out?

Anyway, not meaning to hijack this thread, but since we're mostly on
the R3xx+ hardware page, this might be a good opportunity to take a
look at #389 [1] and #2780 [2] (cc'ing airlied, since he seems to have
access to the hardware). I could be wrong, but it seems to be a stride
calculation issue, easy enough to solve for someone familiar with the
driver (which I'm not :)). This would get us usable DRI3/GLAMOR
support on R3xx+ hardware.

[1] https://gitlab.freedesktop.org/mesa/mesa/-/issues/389
[2] https://gitlab.freedesktop.org/mesa/mesa/-/issues/2780