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. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
