RFC: AGP + nouveau + quirks

[Ilia Mirkin]

On Fri, Oct 11, 2013 at 12:50 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Fri, Oct 11, 2013 at 12:33 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> I was just looking at
>> https://bugs.freedesktop.org/show_bug.cgi?id=20341 (see last comment).
>> Basically he's able to to use the card with agpmode=2 but not the
>> auto-detected agpmode=4. I also saw that the radeon driver has a large
>> quirks list, and it seems silly to reproduce it in nouveau.
>>
>> However the quirks in the radeon driver are a bit odd -- they are per
>> agp chipset/card chipset pair, rather than a blanket max speed for the
>> whole agp chipset. I find this surprising, but I suppose I don't know
>> that much about all this stuff. I was thinking for nouveau, it would
>> just be at the agp chipset level.
>>
>> Do you guys think that it's reasonable to make the quirks list
>> dependent on the agp chipset only? In that case, I can refactor and
>> create The One True List (tm). Otherwise I'll just hack something into
>> nouveau inspired by the radeon list. [Also for the single list, it
>> might be better for the agpgart driver itself to know about the
>> restrictions, but that's probably more refactoring than I care for.]
>>
>> Comments/suggestions/concerns appreciated.
>
> It's very much dependent on combinations of gpus and chipsets in my
> experience.  One could probably distill down the actual quirks to some
> general chipset or GPU specific ones, but unfortunately AGP is getting
> so old now that errata lists for old chipsets and GPUs are probably
> hard to come by.  I don't foresee any new AGP systems any time soon,
> so I'm not sure it's worth putting too much effort into it.

OK, so it sounds like the way forward is for me to compile a chipset
-> maxspeed map for nouveau to use and leave radeon out of it.
Ben/David -- does that sound acceptable to you guys? Basically I'd
take the radeon list's chipsets and apply those maxima to all nouveau
video cards (overridable with agpmode, of course).

  -ilia