Re: xHCI problem? [was Re: Erratic USB device behavior and device loss]

Alan Stern
2016-09-20T14:16:52Z

On Tue, 20 Sep 2016, Ritesh Raj Sarraf wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> On Mon, 2016-09-19 at 13:48 -0400, Alan Stern wrote:
> >
> > This ought to help.  Ritesh, please apply this patch on top of the
> > two earlier ones and let's see what happens.
> >
> > Alan Stern
> >
> >
>
> Please find the logs at the following links. On this boot, I did not see any
> kernel stack being printed.
>
> https://people.debian.org/~rrs/tmp/4.8.0-rc7ulf1alan2+.kern.log
> https://people.debian.org/~rrs/tmp/usb-4.8.0-rc7ulf1alan2+.log

This is a lot better. No more I/O errors.

We still have irregular suspends and resumes, but that's to be
expected. More worrying are the spontaneous disconnects. They don't
seem to be related to the suspend/resume activity.

You can disable suspend for this device entirely by doing:

echo on >/sys/bus/usb/devices/2-4/power/control

I'm afraid that this won't prevent the device from disconnecting
itself, though. This appears to be some sort of hardware bug that
can't be fixed in software.

Alan Stern