On Wed, 6 Feb 2013, Felipe Balbi wrote:

> > I can't reproduce the problem on Panda, but I can on Beagle with a slightly
> > different behaviour.
> > 
> > 1) connecting/disconnecting device directly to the beagleboard's USB port 
> > works fine.
> > 
> > 2) If I connect a USB Hub to the port and connect a device to it after the 
> > hub has
> > autosuspended, the device is never detected.
> > doing lsusb after that triggers the detection and produces a lot of 
> > transaction errors.
> > Beagle log is below, before and after 'lsusb'
> > 
> > I suppose this doesn't affect Panda because it has a hub connected 
> > immediately below the
> > root hub that never suspends (as ethernet is hardwired to it).
> 
> Roger, try changing hub's autosuspend delay to something greater than
> 30ms and see if it helps. There was a discussion lately about that.

There also were some patches to address this problem recently merged by
Greg KH (they are in Linus's current git, added after 3.8-rc6 was 
released):

da0aa7169b97d90f4af39a9dc84d58bbe19d7e78 USB: add 
usb_hcd_{start,end}_port_resume
f292e7f9fb0e4bec68bbd83443407d6bb7922d36 USB: EHCI: notify usbcore about port 
resumes
ee74290b7853db9d5fd64db70e5c175241c59fba USB: EHCI: fix timer bug affecting 
port resume

Alan Stern

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