From: Sarah Sharp [
> On Thu, Jan 16, 2014 at 10:21:11AM +0000, David Laight wrote:
> > From: David Laight
> > > From: David Laight
...
> > > Below is a possible patch, I've only compile tested it.
> > > I've minimalised the patch by not removing all the code that saves
> > > 'start_trb' and modifies the TRB_CYCLE bit.
> > > If the patch works those parts can also be tidied up.
> >
> > I've had some feedback (in a private email) that the patch helps.
> > This was using the ASMedia controller with the asx88179_178a
> > ethernet device.
>
> David, please post the contents of that private email to the list and Cc
> me. We don't debug in private in the kernel.
I'm not sure I should copy private emails to the list without
permission of the person who wrote them.
> > So the theory was definitely on the right lines.
> > And I managed to write the patch without any silly mistakes!
>
> Your theory about the ASMedia host may be correct. There are other host
> controllers (Synopsys, I think) that needed us to not give a link TRB
> over to the host until the TRB it pointed had the cycle bit set to
> hardware owned. ISTR that this was only triggered with USB 3.0 streams,
> at least on that Synopsys host.
>
> (BTW, you can find out why any part of the code was written by using
> `git blame filename`, although the original commit that fixed this bug
> has an entirely unhelpful description.)
>
> So, I agree that this needs to get fixed, especially since full UAS and
> streams support will be landing in the 3.15 kernel. However, I like the
> simple patch you posted much better than the second patch. The second
> patch is much too big to be back ported to stable, and we need to get
> this backported to stable. Please resend your previous patch.
Ok, I'll send it in parts. Probably as a patch set that must be applied
in sequence.
David.
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