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SubjectRe: 2.5.61/usb: ioctl control transfer
On Sat, Feb 15, 2003 at 11:01:22PM +0100, Andreas Jellinghaus wrote:
> I'm using the devfs from a userspace application.
> the ioctl USBDEVFS_CONTROL is supposed to return
> the number of bytes actualy read from a control
> transfer.
>
> but the return code i get is always what i specified
> as length of the buffer.
>
> since i'm using the same usb control transfers
> as the windows drivers and get the same result
> back (but return code is always wLength),
> i wonder if there is a bug in the kernel. Anyone
> has similiar problems?
>
> Regards, Andreas
> (userspace code ...)
> syslog(LOG_DEBUG, "usb xmit %02hx %02hx %02hx %02hx 00 00 %02hx %02hx\n"
> ,
> type, req, value >> 8, value&0xff, size >> 8, size &
> 0xff);
>
> if (! (type & 0x80)) debug_hexdump("Sending:", buf, size);
>
> rc = ioctl(fd, USBDEVFS_CONTROL, &ctrl);
> if (rc == -1) {
> syslog(LOG_ERR, "usb ioctl control transfer failed:%s\n",
> strerror(errno));
> }
> syslog(LOG_DEBUG, "ioctl rc %hx size %hx length %hx",
> rc, size, ctrl.length);
> if (type & 0x80) debug_hexdump("Received:", buf, size);
>
>

I seem to be seeing the same thing with USB-storage devices - usb-storage
sees an error because it got back the same value it sent.
It makes mounting usb-storage devices take a LONG time as each send is
followed by a device reset since the returned value is unexpected.

--
Murray J. Root

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