Re: libusb and usbdevfs

[Greg KH <greg@xxxxxxxxx>]

On Sat, Oct 14, 2006 at 12:05:37PM +0530, pradeep singh wrote:
> [snip]
> >> >> Without a driver i may not be able to communicate to the device like
> >> >> normal read write etc. But shouldnt it be visible to me through sysfs
> >> >> interface?
> >> >
> >> >Yes it should.
> >> Yes it is now visible. But problem is now it recognizes it as webcam
> >> :(. Though it is not. How big is this problem?
> >
> >What is it really?  Why would the kernel be confused this way?
> Greg the device is a USB I/O card. I dont know why is kernel confused
> this way? But it loads the USB serial webcam driver for it , dont know
> why.

What does the kernel say when you plug in your USB device?  You can see
this by running 'dmesg'.

> >
> >> or is it a problem at all? On the other hand can question specially to
> >> Greg :). You rewrote ezusb.c in the source tree for 2.6.x kernel. I
> >> want to use it but i somehow cant. Can i somehow use cypress_m8 module
> >> instead of ezusb module?
> >
> >Please provide specifics as to why you can not use the ezusb.c calls in
> >your driver.  It works for me.
> I havent written the driver yet, so didnt try the ezusb calls:).

They why did you say you can not use it?

> >> I tried but cypress_m8 module doesnot identifies the card at all :(.
> >
> >I don't understand, why would different random drivers work with this
> >device.  What type of device is it?  What is the output of
> >/proc/bus/usb/devices with the device plugged in?
> there is no such thing devices in my /proc/bus/usb/ :(.

Did you select the CONFIG_USB_DEVICEFS option in your kernel
configuration?  If so, just mount it:
	mount -t usbfs none /proc/bus/usb

and then send the output of the file with the device plugged in.

I also suggest that you take a look at the Linux Device Drivers book for
the USB chapter (free online), and the built-in USB documentation in the
kernel ('make psdocs' creates it all.)

Also, there is a skeleton USB driver in drivers/usb/usb-skeleton.c that
will help you out.

If you still have questions after all of that, please ask them on the
linux-usb-devel mailing list.  That's the proper place for this.

good luck,

greg k-h

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