Re: [PATCH] usb: core: allow zero packet flag for interrupt urbs

[Amit Virdi <amit.virdi@st.com>]

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.

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.

Regards
Amit Virdi