Re: Scenario: usbtest test-14 failure: MUSBHDRC + Netchip2280

On Fri, 30 Mar 2007, Pandita, Vikram wrote:

> > From: Alan Stern [mailto:[email protected]]
> > 
> > > @@ -2204,12 +2206,16 @@ static void handle_ep_small (struct net2
> > >  					&& req
> > > 					&& req->req.actual ==
> req->req.length)
> > > 					|| !req) {
> > > +printk("\n-->STALL\n");
> > 
> > Please try printing some additional information:
> > 
> > +printk("\n-->STALL: t %x, req %p\n", t, req);
> > +if (req) printk("actual %d, length %d\n", req->req.actual, req-
> > >req.length);
> > 
> 
> The log shows:
> -->STALL: t 41042a, req 00000000
> Which means: ep->responded is 1.
> Does this help?

It helps.  But I don't understand what it signifies!

First of all, the fact that req is NULL and ep->responded is 1 means that
as far as the net2280 driver is concerned, the data stage of the control
transfer is over and allow_status() has been called.  This means that on a 
previous trip through handle_ep_small(), mode was set to 2 and hence an IN 
token has already been received (although the response to the IN could 
have been NAK instead of ACK).

The bits in t are:

	0x400000	HIGH_BANDWIDTH_OUT_TRANSACTION_PID = Data1
	0x010000	USB_OUT_ACK_SENT
	0x000400	FIFO_EMPTY
	0x000020	SHORT_PACKET_TRANSFERRED_INTERRUPT
	0x000008	DATA_PACKET_RECEIVED_INTERRUPT
	0x000002	DATA_OUT_PING_TOKEN_INTERRUPT

As near as I can see, this means the net22800 got an OUT token followed by
a 0-length DATA1 packet.  If that was really what happened (OUT/DATA after 
an IN packet for the status stage) then responding with STALL was the 
correct thing to do.  However it disagrees completely with the CATC trace.

Does this mean the net2280 has generated a bogus IRQ?  That's what it 
looks like.

> Another observation:
> Running the netchip test14 with Intel 82801GB EHCI controller does not
> show PING being sent after a NYET response.
> 
> So its not clear what the Host behavior is after it gets a NYET?
> Is there an existing EHCI that has this behavior?

I don't know.  Maybe Dave does.

Alan Stern


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