RE: [BUG] usb_dev_resume returns -113 due to work items queued by usb on pm_wq is not executed before suspending.

[Alan Stern]

On Mon, 18 Aug 2014, Du, ChangbinX wrote:

> > On Fri, 15 Aug 2014, Du, ChangbinX wrote:
> > > If my analysis is correct, could you share your ideas for this issue?
> > 
> > Hasn't this already been fixed?  See commit d6236f6d1d88 (xhci: Fix runtime
> > suspended xhci from blocking system suspend).
> > 
> > Alan Stern
> 
> Hi, Stern,
> These are two different issues. Commit d6236f6d1d88 fixes issue that xhci runtime
> pm logical blocks system suspend. But the issue we are encountering is usb device
> resuming fail and lead to device reset.

Yes, the issues are different, but I think the fix is the same.  You
should test a kernel that includes commit d6236f6d1d88.

> This issue can be reproduced by below steps:
> 1) Plug a usb device to usb3 host, and make sure this device can enter runtime
>   suspend state.
> 2) Wait HCD entering runtime suspend state.( xhci_suspend() will be called)
> 3) Make system starts system suspending. On this step, PM core freeze threads and
>   resume hcd & the usb device to runtime active state(xhci_resume() will be called, 
>   and roothub resuming work item is queued). Then calls the suspend callbacks of devices'.

Commit d6236f6d1d88 prevents the roothub resuming work item from being
queued.

> 4) We force system suspending process aborted (by modifying code) just after the usb
>   Device suspend callback is invoked.
> 5) Then PM core will call resume callback of the usb device to recovery. On this step
>   usb_dev_resume() invokes and it return -113 error. Because the can_submit flag of
>   root hub is 0. Root hub resuming work item is still pending.

I still think that commit has already fixed your problem.

Alan Stern

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