Re: rt8192cu on USB3

[Sarah Sharp <sarah.a.sharp@linux.intel.com>]

On Thu, Mar 22, 2012 at 09:24:31PM -0500, Larry Finger wrote:
> On 03/22/2012 05:31 PM, Sarah Sharp wrote:
> 
> >Larry, if the driver doesn't cancel an URB that the device doesn't
> >respond to, then it will just be left on the endpoint ring.  If the
> >driver then tries to queue new transfers to that same endpoint, but the
> >device keeps NAKing the uncancelled transfer, then the endpoint ring
> >would fill up with unanswered transfers.
> >
> >Perhaps some userspace or kernel portion is forgetting to cancel URBs
> >before moving onto the next thing?  You said you moved to asynchronous
> >transfers, so maybe the problem lies there?
> 
> The writes have always been asynchronous and reads are synchronous.
> The only change was to convert the firmware uploading writes from
> 32-bits at a time into block writes of 1000+ 32-bit words.

Yeah, that's going to cause the out-of-room warning under xHCI.  That
should be fixed in the 3.4-rc1 kernel though.

> Would xhci be worse that ohci or ehci in terms of the device not
> responding to URBs? We only see problems with USB3.0 hubs, never
> with 2.0 or 1.1.

That's because EHCI handles arbitrarily large transfers, and xHCI didn't
until now.

> I am looking into changing the writes to be synchronous. That should
> clear up any problems.

Yeah, your problem probably was in the bulk large transfer, not the
unfinished canceled URBs.  I would suggest getting your reporters to
just try 3.4-rc1 and see if it helps before doing too much work to debug
this.

Sarah Sharp