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

Alan Stern
2016-09-20T15:43:10Z

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

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> Hello Alan,
>
> On Tue, 2016-09-20 at 10:16 -0400, Alan Stern wrote:
> > 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
> >
>
> Yes. But that'd also mean to write that value upon every suspend/resume cycle
> because the rtsx usb driver still declares support for autosuspend.
> Should that be dropped ?

No, the value doesn't change across a suspend/resume cycle.

> > 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.
>
> And that'd mean that upon every reset, the driver will again enable autosuspend
> for that driver.

Yes, that's true. I'm curious to see if preventing autosuspends will
get rid of the resets. My guess is that it won't.

Alan Stern