Am 31.08.2018 um 09:30 schrieb Daniel Drake:
On over 40 Intel-based Asus products, the nvidia GPU becomes unusable
after S3 suspend/resume. The affected products include multiple
generations of nvidia GPUs and Intel SoCs. After resume, nouveau logs
many errors such as:
fifo: fault 00 [READ] at 0000005555555000 engine 00 [GR] client 04 [HUB/FE] reason 4a [] on channel -1 [007fa91000 unknown]
DRM: failed to idle channel 0 [DRM]
Similarly, the nvidia proprietary driver also fails after resume
(black screen, 100% CPU usage in Xorg process). We shipped a sample
to Nvidia for diagnosis, and their response indicated that it's a
problem with the parent PCI bridge (on the Intel SoC), not the GPU.
We found a workaround: on resume, rewrite the Intel PCI bridge
'Prefetchable Base Upper 32 Bits' register. In the cases that I checked,
this register has value 0 and we just have to rewrite that value.
It's very strange that rewriting the exact same register value
makes a difference, but it definitely makes the issue go away.
It's not just acting as some kind of memory barrier, because rewriting
other bridge registers does not work around the issue. There's something
magic in this particular register.
We examined our database of Asus hardware and identified 43 products
that we believe are affected. Checking the nvidia GPU parent PCI bridge
on each one, in total 5 Intel PCI bridges need quirking as below.
The quirk will run on bridges even where no nvidia GPU is connected,
but it should be harmless, and we at least limit it to only running
on Asus products.
This fix was tested on all the affected models that we have in hands
(X542UQ, UX533FD, X530UN, V272UN).
Hello,
this patch helps on my HP Zbook 14u G5 which otherwise fails to resume
the dGPU after suspend. In this case it's a radeon gpu (polaris 10). Of
course I had to remove the check for ASUS, but made no other changes.
With this patch I can successfully run "DRI_PRIME=1 glxinfo | grep -i
renderer" and see the radeon, as well as "DRI_PRIME=1 glxgears", after
resuming from suspend. Attemting that without the patch makes the system
hang for a few seconds followed by lots of powerplay errors in dmesg.
glxinfo/gears sometimes use the Intel graphics or show a blank window.
FWIW, this problem was discussed a lot in bug
https://bugs.freedesktop.org/show_bug.cgi?id=105760 (it's closed only
because the original bug crash is solved but the root problem is still
unfixed). Therefore I add Peter Wu and Alex Deucher who attempted to
help me out already.
I think this supports your other mail where you suggest it should be
done unconditionally.
Thanks for the patch!
Best regards
