Thomas Wahrenbruch wrote:
> Hi all,
>
> I'm writing a driver for our (custom-made) USB-serial converter using
> the usb_serial module. In order to setup the converter I have to send
> some Control URBs to the converter. Sending one Control URB works fine.
> But if I want to send more than one Control URB, I have to wait for the
> completion hanlder to finish, before I can send the next URB. (Please
> correct me, if I'm wrong) I need the result of the previous Control URB
> to determine what Control URB to send next.
>
> Now here comes my question: How do I wait?
>
> I tried to wait with wait_queue and wake_up, but the kernel hangs.
> Kernel 2.4.18-3 (Red hat 7.3)
Are you familiar with the use of those functions ? Seeing the actual
code could help.
>
>
> Kind regards
>
> Thomas Wahrenbruch
>
>
>
>
> static void my_complete( struct urb *purb )
> {
> char* p_dummy;
> int i;
> struct usb_serial_port *port;
>
> p_dummy = purb->transfer_buffer;
> printk(KERN_DEBUG "Transfer Buffer: ");
> for (i = 0; i < 8; i++) {
> printk(KERN_DEBUG "%02X ", (short)( p_dummy[i] & 0x00FF) );
> }
> usb_unlink_urb( purb );
Unlinking this urb isn't necessary.
> // notify ?!
You would issue a wakeup() here.
> }
>
>
> static int open()
> {
> FILL_CONTROL_URB(.....);
> result = usb_submit_urb( my_urb );
>
> // wait for completion handler !
>
> if (transfer_buffer[x] == z) {
> FILL_CONTROL_URB(.....);
> result = usb_submit_urb( my_urb );
> } else {
> ....
> }
> return 0;
> }
>
>
In your case, you could issue blocking URBs (using usb_control_msg).
See: http://usb.cs.tum.edu/usbdoc/node26.html
It's supposed to be a wrapper for an old API, but it's not marked as
deprecated, so I guess you can use it.
If you really want to use usb_submit_urb, here is a code sniplet showing
an (hopefuly!) correct usage:
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&iforce->wait, &wait);
if (usb_submit_urb(iforce->ctrl, GFP_KERNEL)) {
set_current_state(TASK_RUNNING);
remove_wait_queue(&iforce->wait, &wait);
return -1;
}
while (timeout && iforce->ctrl->status == -EINPROGRESS)
timeout = schedule_timeout(timeout);
set_current_state(TASK_RUNNING);
remove_wait_queue(&iforce->wait, &wait);
if (!timeout) {
usb_unlink_urb(iforce->ctrl);
return -1;
}
Looking at this code now, I wonder if reading iforce->ctrl->status is ok ?!
--
Johann Deneux
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