Re: EOVERFLOW problem with usb_control_msg

Alan Stern <[email protected]>
Newsgroups gmane.linux.usb.devel
Message-ID <[email protected]>
On Mon, 20 Aug 2007, Frank Kingswood wrote:

> Hallo!
> 
> I am trying to develop a kernel module for the CH341 USB-to-serial 
> adaptor. I have working libusb code which sets up the device, but am 
> having problems repeating this in the kernel.
> 
> The first control message that reads data from the device returns with 
> -EOVERFLOW, which the documentation describes as the USB device 
> babbling. There is no data on the bus, however.

Try using usbmon (see Documentation/usb/usbmon.txt).  How do you know 
there is no data on the bus?

> I have tried tracing through the code in usb_control_msg (down to 
> wait_for_completion_timeout) but don't see this error value being
> generated.

It isn't generated in any of those routines; it comes from the host 
controller driver.

Alan Stern


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