[Nouveau] Handling GeForce GTX 850M GPU on Arch Linux

[caocoa at mail2tor.com]

Hello all,

I've juste installed a new computer and I feel like I'm having trouble
with my NVIDIA GPU but it could be something else so I've enclosed
detailed output. As you can see in [lspci] output, my GPU is `NVIDIA
Corporation GM107M [GeForce GTX 850M] (rev a2)` whose specification can be
found in [specs].

The trouble I'd like to solve has the following symptoms:
 --> Sometimes during booting process, it issues a lot of lines like
`nouveau E[   PFIFO][0000:01:00.0] SCHED_ERROR [ UNK06 ]` (see [dmesg]
output for full details). This seems to appear randomly: sometimes the
computer has to reboot automatically two or three times before being able
to boot correctly, sometimes it just needs once and doesn't have nay
troubles.
 --> Some other times, windows appear to stop responding with no
reasons. I have to move the pointer off so the window display will
unfreeze and then I can put the pointer over again. I've found it seems to
be related to lines like this one `nouveau E[   PIBUS][0000:01:00.0] HUB0:
0x000001 0x00000002 (0xbad00100)` in [dmesg]. It starts at timestamp
28.115820.
 --> Sometimes, even my window manager (Gnome 3) freezes and I have to
go to a tty to have a chance to unfreeze it. It doesn't always work
then sometimes I have to reboot my computer because it has become
absolutely frozen (no mouse, no keyboard, even the keyboard CAPS light
responds no more).

I'm quite puzzled by this and I don't know whether the last symptom is a
bug or a feature (maybe multiple user simultaneous outputs). I've also
enclosed for your information my [Xorg.0.log] file and [lsmod] output. One
suggested me to share that with nouveau mailing list: maybe you don't have
any GeForce GTX 850M to test. I would agree to take time and perform test
for you if it can help to improve the way driver nouveau handles recent
GPU :)

Just feel free to ask any further data you'd need about my configuration.

Thank you in advance for you reply and have a good week!

Caocoa

--- references
[lspci] https://pastee.org/mtwkr
[specs] http://www.geforce.com/hardware/notebook-gpus/geforce-gtx-850m
[dmesg] https://pastee.org/zd4tt
[lsmod] https://pastee.org/t5z4e
[Xorg.0.log] https://pastee.org/r5tak