[Nouveau] [Bug 54437] [NVC8] linux-nouveau2.6 (3.6.0-rc4) : GTX580 : Xorg freezes when using accel

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=54437

--- Comment #13 from Ilia Mirkin <imirkin at alum.mit.edu> ---
(In reply to comment #12)
> This bug is affecting me also, see the last duplicated bug. Any progress in
> fixing this? Maybe some help in testing (for ex.) required?

It's a bit of a mystery unfortunately. Adding to the annoyance, Ben said that
it does work just fine on his NVC8, although he has the less powerful versions.
Could be something with high ROP/TPC/GPC counts not being handled. (Or multiple
PARTs?)

That might actually be an interesting experiment -- before loading nouveau,
mask out a bunch of the units and see if it helps. If it does, find the
"breaking" point.

This is the code that computes that stuff:

http://cgit.freedesktop.org/~darktama/nouveau/tree/nvkm/engine/graph/nvc0.c#n1330

    priv->rop_nr = (nv_rd32(priv, 0x409604) & 0x001f0000) >> 16;
    priv->gpc_nr =  nv_rd32(priv, 0x409604) & 0x0000001f;
    for (i = 0; i < priv->gpc_nr; i++) {
        priv->tpc_nr[i]  = nv_rd32(priv, GPC_UNIT(i, 0x2608));
        priv->tpc_total += priv->tpc_nr[i];
    }

Step 1: Print out the various values (i.e. number of ROPs, GPCs, and the
per-GPC TPC counts).
Step 2: Artificially lower them (to, e.g., 1) and see if it helps. If it does,
figure out which of the values matter and where the breaking points are.

If it doesn't help, perhaps the units need to be disabled a little harder, e.g.
by setting 0x22584/0x22588.

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