Comme=
nt # 12
on bug 10194=
6
from Robin
Created attachment 133103 [details]
case2-rescan-amd.sh
In an attempt to make a second test case I've created a new script that
produced some noteworthy results.
Rather than bind/unbind, this approach uses rmmod,modprobe, removing the pci
device and rescanning to switch drivers.
Please excuse how poorly written and contrived the test case for "hots=
wapping"
proposes, I'll try isolating what causes the differences with the first test
case in some mutations next, but wanted to share the intermediate results a=
s-is
first.
Some details about this test.
The starting point is the same as the other test case, TTY and vfio-pci tak=
ing
the card first. In order it will:
1. rmmod the current driver.
2. remove one pci subdevice (either VGA or Audio)
3. modprobe the new driver.
4. perform a pci rescan.
It will do this in a loop switching between amdgpu and vfio-pci again.
Another difference is that snd_hda_intel is in use elsewhere, it does not g=
et
an rmmod and will not switch back to vfio-pci because of this.
---
As for results, on 4.10 there was no change.
>>From the 2nd binding onward this error will fail to init the driver.
> [ 160.013733] [drm:ci_dpm_enable [amdgpu]] *ERR=
OR* ci_start_dpm failed
> [ 160.014134] [drm:amdgpu_device_init [amdgpu]] *ERROR* hw_init of IP=
block <amdgpu_powerplay> failed -22
For 4.13rc2, drm-next-4.14-wip and drm-next-4.14-wip with patch 3 it's a
different story.
They have an irregular pattern of errors every loop.
Either the 2nd or 3rd time the first error crops up. Typically this is:
> [ 211.818341] [drm:cik_sdma_ring_test_ring [amd=
gpu]] *ERROR* amdgpu: ring 9 test failed (0xCAFEDEAD)
> [ 211.818725] [drm:amdgpu_device_init [amdgpu]] *ERROR* hw_init of IP=
block <cik_sdma> failed -22
After that first error, additionally the following error can appear as well.
> [ 247.626839] [drm:gfx_v7_0_ring_test_ring [amd=
gpu]] *ERROR* amdgpu: ring 1 test failed (scratch(0xC040)=3D0xCAFEDEAD)
And instead of ring 9, ring 10 may fail.
> [ 356.686092] [drm:cik_sdma_ring_test_ring [amd=
gpu]] *ERROR* amdgpu: ring 10 test failed (0xCAFEDEAD)
> [ 356.686580] [drm:amdgpu_device_init [amdgpu]] *ERROR* hw_init of IP=
block <cik_sdma> failed -22
They seem to randomly happen in the following combinations:
A. Ring 1 fails.
B. Ring 9 or 10 fails.
C. Ring 1 + Ring 9 or 10 fails.
Most importantly though. Only if 9 or 10 fail (B or C combinations) will the
hw_init error occur. If it's just a ring 1 failure (A) the driver will
successfully init the GPU.
Also, the drm-next-4.14-wip with patch 3 kernel will have this A combination
and successful init a lot more often that the other two.
---
So my suspicion is that this difference could be due to:
- Repeatedly rmmodding and modprobing being part of the loop now.
- The rescanning method vs bind/unbind.
- The different treatment of the Audio component.
- The different access of vfio-pci to the Audio component.
So I will make several variations on the test scripts to try and narrow this
down.