reading USB data through usbdevfs

[Viral Mehta <Viral.Mehta@xxxxxxxxxxxxxxx>]

Hi,

I am writing USB user space driver on Host side. It is not following any class but a vendor specific.
It is doing Bulk IN and OUT transfers. Device side gadget driver is doing Bulk Write and Host is waiting for the data.

Now, on the host side I am doing in the userspace,
{
    For loop for 1024 times
    {...
        Fill urb struct
        urb->buffer_length = len;

        ioctl(h->desc, USBDEVFS_SUBMITURB, urb);

        ioctl(h->desc, USBDEVFS_REAPURB, &urb_reap);
    }
}

However, everytime I reaped URB, it gets the same data. For all 1024 times. And the data is the part (of length = urb->buffer_length) of first URB submitted from gadget side. All urb struct and buffers are maintained properly.

Interestingly, if I change length (urb->buffer_length = len) such that it matches with what gadget side driver is sending (or doing urb_submit), I start getting proper data each time.

Looks like a Bug somewhere in usbdevfs. ??

Thanks,
Viral Mehta


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