On Mon, 23 Jul 2012, Bjørn Mork wrote:
> Alan Stern <st...@rowland.harvard.edu> writes:
> > On Mon, 23 Jul 2012, Bjørn Mork wrote:
> >
> >> Hello,
> >>
> >> I have no idea where to start debugging this. But USB hotplug does not
> >> seem to work at all in linux-next if autosuspend is enabled.
> >>
> >> I am running next-20120723 with this:
> >>
> >> nemi:/tmp# grep . /sys/bus/usb/devices/usb*/power/control
> >> /sys/bus/usb/devices/usb1/power/control:auto
> >> /sys/bus/usb/devices/usb2/power/control:auto
> >> /sys/bus/usb/devices/usb3/power/control:auto
> >> /sys/bus/usb/devices/usb4/power/control:auto
> >> /sys/bus/usb/devices/usb5/power/control:auto
> >> /sys/bus/usb/devices/usb6/power/control:auto
> >> /sys/bus/usb/devices/usb7/power/control:auto
> >> /sys/bus/usb/devices/usb8/power/control:auto
> >>
> >>
> >> Connecting a device to any port, whether it is external or internal
> >> (using rfkill to "connect") has no effect. Nothing in the log. No
> >> uevent.
> >>
> >> Setting control to "on" on a port will reenable hotplug on that port.
> >> Any device connected while in "auto" state will suddenly be discovered.
> >
> > This sounds like a bug in the host controller driver. What HCDs are
> > you using? Does the host controller also get suspended?
>
> uhci_hcd + ehci_hcd. Really standard intel based laptop from 2008/2009:
I tried reproducing this without success. But I wasn't using the same
kernel as you; I used 3.5 plus Greg's usb-next branch. So it looks
like the problem lies somewhere else.
At any rate, you should be able to prevent the problem by preventing
the host controllers from suspending in the first place:
for a in /sys/bus/usb/devices/usb* ; do
echo on >$a/../power/control
done
Alan Stern
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