[Nouveau] [PATCH/TESTING(all hw)/DISCUSSION] FIFO (minor) create and (major) destroy instabilities on nv50+

[Ben Skeggs]

On Mon, 2010-01-04 at 20:29 +0100, Maarten Maathuis wrote:
> I've narrowed it down further, the "pgraph->fifo_access" bit is still
> cleanup (register 0x400500 represents pgraph fifo access), the rest
> appears needed for the desired effect. The reordering of pfifo and
> pgraph destroy is needed. As usual, feedback is appreciated.
I played a bit yesterday and have the gr/fifoctx unload ordering swap
and queued up already, as well as unconditionally waiting on a fence at
channel destroy (not really needed, but served as a bit of a cleanup
anyway).

I'll try and look at the rest of the changes.

Ben.
> 
> Maarten.
> 
> On Sat, Jan 2, 2010 at 4:36 PM, Maarten Maathuis <madman2003 at gmail.com> wrote:
> > Many people using nv50+ hardware are aware of gpu lockups when a fifo
> > closes under certain conditions. Based on a mmio-trace and some trail
> > and error testing i've come up with a patch that improves the
> > situation on my NV96.
> >
> > This patch needs testing on NV50+ hardware and regression testing on
> > older hardware, since i did change some of the common codepaths. This
> > is very much a work in progress, and if you have anything to
> > add/correct, please share it.
> >
> > I've also attached a 2 test apps, once is bitscan-fail from mwk, use
> > it like ./bitscan-fail 0x200 to trigger PGRAPH errors. A modified
> > version only emits NOPs (method 0x100) and represents the no error
> > situation.
> >
> > For me, i can run the NOP program in loops of 10000 iterations with no
> > problems (i've done so several times), the bitscan-fail survives 10000
> > iterations sometimes, but can also fail after a few thousand. In
> > comparison, a single run of bitscan-fail could cause a gpu lockup for
> > me in the past.
> >
> > Please try the gallium driver, the test apps, suspend to ram. Suspend
> > to ram isn't 100% reliable yet for me (this was always the case after
> > strange experiments/hammering/etc), but should not regress. This goes
> > for older hw as well, whatever worked should still work, but i
> > wouldn't expect serious improvements there.
> >
> > As always, feedback is appreciated, especially since this is a touchy subject.
> >
> > Maarten.
> >
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