On Wed, 13 Feb 2002, Roland King wrote:
>The device has interrupt endpoints. I see special transfer ioctls >for bulk, but not interrupt. I've been assuming that I need to >submit a usbdevfs_urb and then go and reap it. Does that sound >about right? Is there any sample code or a good example which >uses these functions? Yes, you submit a BULK type usbdevfs_urb to the interrupt endpoint. It gets one packet of data. You can submit multiple ones that will queue up. and I'm guessing 'reap' is REAd Pointer, not like the grim reaper (although maybe it is...:) >Unrelated question, if you're writing a normal device driver and >your device has interrupt endpoints and you submit an interrupt >urb, will you be called each time there's an interrupt continuously >until you unlink the urb, or do you have to resubmit it? I found one Yes, unless you're on UHCI hardware and interval == 0. OHCI resubmits regardless of interval. On UHCI, 0-interval behaves like BULK (except for its priority). Note you should not use interrupt type usbdevfs_urbs if your hardware is OHCI, as OHCI will resubmit it http://lxr.linux.no/source/drivers/usb/usb-ohci.c#L486 then you reap it http://lxr.linux.no/source/drivers/usb/devio.c#L978 which frees the URB (part of the struct async) http://lxr.linux.no/source/drivers/usb/devio.c#L188 and then bad things happen (kernel accessing freed memory). -- Dan Streetman [EMAIL PROTECTED] -------------------------------------------------- 186,282 miles per second: It isn't just a good idea, it's the law! _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
