[quoted lines by Alan Stern on 2012/04/06 at 10:22 -0400]
>There's nothing special about setting reports; all you do is a normal
>interrupt-OUT transfer.
Thanks. Where does the report number and/or any other required information go?
Should it just be put in a byte which is prepended to the data? For example, to
set report 3 to the three characters "abc", should we actually write {0X03,
0X61, 0X62, 0X63}?
>With usbfs, you can send an interrupt transfer the same way you would
>send a bulk transfer: the USBDEVFS_BULK ioctl. Or if you prefer, you
>can use the async interface with USBDEVFS_SUBMITURB, where urb->type is
>set to either USBDEVFS_URB_TYPE_INTERRUPT or USBDEVFS_URB_TYPE_BULK
>(the kernel will accept either one when urb->endpoint refers to an
>interrupt endpoint).
Our code looks like this:
case UsbEndpointTransfer_Interrupt:
case UsbEndpointTransfer_Bulk:
return usbBulkTransfer(endpoint, (void *)buffer, length, timeout);
/*
case UsbEndpointTransfer_Interrupt: {
struct usbdevfs_urb *urb = usbInterruptTransfer(endpoint, (void *)buffer, length, timeout);
if (urb) {
ssize_t count = urb->actual_length;
free(urb);
return count;
}
break;
}
*/
So we actually do it the easier way, but also keep the harder way hanging
around in a comment.
>Of course, if you're using usbfs then you have to detach the normal
>usbhid kernel driver from the interface first. Presumably you're
>already aware of what that entails.
Yes. We have code for that as well since it also has to be done for a number of
non-HID USB to serial adapters. We do, in fact, already support other HID-based
braille devices - it's just that this is the first one which requires an
interrupt transfer to set a report.
Even though we already do most of what's necessary, I still do very much
appreciate your complete answer just in case we weren't.
I think we now just need to know where to put the report number, and whatever
other information may also need to be added to the data.
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