Re: [Libusb-devel] Can't write to a device

[Xiaofan C. <xia...@gm...>]

On 10/23/07, Brad Schick <sc...@gm...> wrote:
> I have a usbhid device that I am using libusb (actually pyusb) to
> communicate with. The first problem I had was the device always being
> busy when claiming an interface. I solved that by unbinding the kernel
> usbhid driver with:
>
>  echo -n "2-1:1.0" > /sys/bus/usb/drivers/usbhid/unbind
>
> That at least lets me open the device and claim the interface from my
> application. But when I try to do an interrupt_write to an endpoint I
> get the following error.
>
> usb.USBError: error submitting URB: No such file or directory
>
> Another strange thing is that if I try to rebind the usbhid driver with:
>
> echo -n "2-1:1.0" > /sys/bus/usb/drivers/usbhid/unbind
>
> I get the following error:
>
> bash: echo: write error: No such device
>
> But I can see that the device is still listed under
> /sys/bus/usb/devices, and it is not bound to a driver.
>
> Any suggestions? I'm fairly new to usb development, so I'm not sure
> where to get more info. I haven't found any logs with info or much by
> searching the net. I am running Ubuntu 7.10 32bit, kernel
> 2.6.22-14-generic, libusb 0.1.12-7, python-pyusb 0.3.5-4.
>

What does "lsusb -v" say?

And try to disable auto-suspend by recompiling the kernel. You
may have a firmware bug which does not handle suspend-resume
properly. This may or may not be your problem. From 2.6.23 onwards,
auto-suspend will be not be enabled by default because so many
USB device are buggy dealing with suspend/resume.

Reference:
My Problem:
http://forum.microchip.com/tm.aspx?m=283378
http://sourceforge.net/mailarchive/forum.php?thread_name=1189786321l.13173l.12l%40mofo&forum_name=libusb-devel

Solution from Linux USB developers:
http://forum.microchip.com/tm.aspx?m=275422&mpage=2
http://sourceforge.net/mailarchive/forum.php?thread_name=1189786321l.13173l.12l%40mofo&forum_name=libusb-devel


Xiaofan
http://mcuee.blogspot.com