Question regarding short transfers

Hi
I have two questions regarding short transfers.
My questions are best illustrated by a scenario:

Lets say the Hosts Mass Storage driver wants to READ 12K:

I believe that the Host Controller driver (e.g. ehci_hcd) might see
something like this coming from usbcore:

1) BULK OUT urb (31 bytes) [Contains READ10 command]
2) BULK IN  urb (4K)       [data]
3) BULK IN  urb (8K)       [data]
4) BULK IN  urb (13 bytes) [status]

I have two questions regarding what happens when the transfer gets
terminated early:


1) What happens if the device terminates the transfer after the 4KB
(with a zero-length packet)?  

Does the HC driver...
- set status to 0 in the 4K urb (& actual_length=4096) and
- flush all other queued urbs for that EP (in this case the 8K urb) by
completing them with an error status ?  If so what is the status ?



2) What happens if the device terminates the transfer during the 4KB
(after say 3700 bytes received, with a short packet)?  

Thus:
urb->transfer_buffer_length = 4096
urb->actual_length          = 3700

I believe that the HC driver should do the following test:

if( (urb->actual_length < urb->transfer_buffer_length) &&
	(urb->transfer_flags & URB_SHORT_NOT_OK) )
 	urb->status = -EREMOTEIO;

So if URB_SHORT_NOT_OK is set then -EREMOTEIO will be returned And if
URB_SHORT_NOT_OK is not set the 0 will be returned.

Is this correct ?

Again I assume that the 8K urb should be completed immediately ?
If so with what status ?


I'm having trouble understand the EHCI code; In the EHCI driver where
are these situation handled ?  qh_completions() ?

Thank you for your time
regards
dom



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