Software based unplug of USB device?

Software based unplug of USB device?

[Joerg Pommnitz]

Hello listees,
we are struggling with a 3rd party USB device. It comes with its own
firmware and its own Linux USB serial drivers. Unfortunately the
communication between the device and the user application seems to break
down from time to time. This situation can easily be resolved by
unplugging and then re-plugging the device. Unfortunately this requires
manual intervention.
While resolving the real issue would be the preferred way to deal with
this problem, we would settle for a way to do a software unplug/re-plug.
Can this be done at all? If so, is there a tool to do this?

A detailed description of our environment:
* Linux 2.4.21 with USB OHCI driver
* Natsemi Geode integrated CPU/Chipset

Thanks in advance
  Joerg


	

	
		
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Re: Software based unplug of USB device?

[Duncan Sands]

On Monday 03 May 2004 12:21, Joerg Pommnitz wrote:
> Hello listees,
> we are struggling with a 3rd party USB device. It comes with its own
> firmware and its own Linux USB serial drivers. Unfortunately the
> communication between the device and the user application seems to break
> down from time to time. This situation can easily be resolved by
> unplugging and then re-plugging the device. Unfortunately this requires
> manual intervention.
> While resolving the real issue would be the preferred way to deal with
> this problem, we would settle for a way to do a software unplug/re-plug.
> Can this be done at all? If so, is there a tool to do this?
>
> A detailed description of our environment:
> * Linux 2.4.21 with USB OHCI driver
> * Natsemi Geode integrated CPU/Chipset

This can be done in a number of ways:
(1) unload and reload the module driving the usb device.  This should disconnect
it from the device and reconnect it when reloaded.
(2) restart the hotplug system (this will disconnect and reconnect all devices).
(3) use usbfs: there is an ioctl to disconnect a kernel driver from a device,
and another to reconnect it.

I hope this helps,

Duncan.

Re: Software based unplug of USB device?

[Greg KH]

On Mon, May 03, 2004 at 12:21:20PM +0200, Joerg Pommnitz wrote:
> Hello listees,
> we are struggling with a 3rd party USB device. It comes with its own
> firmware and its own Linux USB serial drivers.

Which device and driver is this?  Do you have a pointer to the driver?

> Unfortunately the
> communication between the device and the user application seems to break
> down from time to time. This situation can easily be resolved by
> unplugging and then re-plugging the device. Unfortunately this requires
> manual intervention.
> While resolving the real issue would be the preferred way to deal with
> this problem, we would settle for a way to do a software unplug/re-plug.

Do you want to do this from within the kernel, or from userspace?  If
from within the kernel, you should be able to drop the power to a hub
port and reenable it, but I haven't checked to see if that works in a
long time.

thanks,

greg k-h

Re: Software based unplug of USB device?

[Johannes Erdfelt]

On Mon, May 03, 2004, Greg KH <greg@kroah.com> wrote:
> On Mon, May 03, 2004 at 12:21:20PM +0200, Joerg Pommnitz wrote:
> > Hello listees,
> > we are struggling with a 3rd party USB device. It comes with its own
> > firmware and its own Linux USB serial drivers.
> 
> Which device and driver is this?  Do you have a pointer to the driver?
> 
> > Unfortunately the
> > communication between the device and the user application seems to break
> > down from time to time. This situation can easily be resolved by
> > unplugging and then re-plugging the device. Unfortunately this requires
> > manual intervention.
> > While resolving the real issue would be the preferred way to deal with
> > this problem, we would settle for a way to do a software unplug/re-plug.
> 
> Do you want to do this from within the kernel, or from userspace?  If
> from within the kernel, you should be able to drop the power to a hub
> port and reenable it, but I haven't checked to see if that works in a
> long time.

Wouldn't usb_reset_device() work? That's assuming the device isn't
totally and completely hosed.

It can be done via usbfs as well.

JE