On 7/18/2014 8:09 PM, Alan Stern wrote:
On Fri, 18 Jul 2014, Amit Virdi wrote:
On 7/17/2014 8:25 PM, Alan Stern wrote:
I can't say this is actually wrong, but have you ever encountered a
situation where this would be needed? How often does anyone need to do
a multi-packet transfer over an interrupt endpoint?
Honestly, I haven't found any such real device yet. I did this change
while I was going through the code when adding support for interrupt
transfers in gadget zero. I'm a no expert, but the spec says it should
be supported so this code should be added.
I just remembered, the HID spec requires that all reports (except the
longest) end with a short packet. And since output reports are allowed
to be sent over an Interrupt-OUT endpoint, we have to accept the
URB_ZERO_PACKET flag for interrupt URBs.
Ok, great!
However, I messed up a little in this patch. It should have been
---
case USB_ENDPOINT_XFER_ISOC:
allowed |= URB_ISO_ASAP;
break;
+ case USB_ENDPOINT_XFER_INT:
+ if (is_out)
+ allowed |= URB_ZERO_PACKET;
+ else
+ allowed |= URB_SHORT_NOT_OK;
+ break;
}
allowed &= urb->transfer_flags;
---
Otherwise, it sets zero packet flag for control out transfers too.
I'll send a V2 with this change if you agree to setting of the zero
packet flag for interrupt transfers.
How about this change instead?
URB_FREE_BUFFER);
switch (xfertype) {
case USB_ENDPOINT_XFER_BULK:
+ case USB_ENDPOINT_XFER_INT:
Looks better.
I'll submit a V2 with this change.
Regards
Amit Virdi
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