Re: broken access to a USB HID device after suspend

[Alan Stern]

On Wed, 12 Mar 2008, Jiri Kosina wrote:

> On Wed, 12 Mar 2008, Tino Keitel wrote:
> 
> > I use a tool called hidmon to control the parameters of my LCD in shell
> > scripts. I just had the case where this tool didn't work after suspend
> > to RAM. I just got this error message:
> > 
> > hid_force_open failed with return code 13
> > 
> > The kernel log contains lines like this:
> > 
> > usb 1-1.3: usbfs: USBDEVFS_CONTROL failed cmd hidmon rqt 129 rq 6 len 9 ret -110
> > 
> > Unplugging and replugging the USB cable of the LCD didn't work.
> > However, after a further suspend/resume cycle it works.
> > 
> > This is Linux 2.6.25-rc5. The behaviour is not repoducible, though.
> > However, I just mention it for the case that this might ring a bell
> > somewhere.
> 
> This in fact looks like a problem with usbdevfs and/or libusb library, not 
> the in-kernel HID drvier.
> 
> Did this work before? In 2.6.24? 2.6.23? Alan (added to CC, as well as USB 
> devel mailinglist) has been doing some changes to usbdevfs to make it 
> suspend-aware, if I recall correctly.

No, usbfs hasn't undergone any significant changes recently.

Tino, it would help to see a kernel log showing what happened during 
the suspend, resume, and failure of hidmon.  It would help even more if 
you test under a kernel with CONFIG_USB_DEBUG enabled.

Even if you can't reproduce the problem, do you have the complete 
kernel log from before?

Is it possible that this is really a problem with the LCD device, not 
with the kernel?  I ask because if the device was working properly then 
unplugging and replugging the USB cable should do a complete reset.

Alan Stern

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