On Wed, Feb 05, 2014 at 04:23:50PM -0500, Alan Stern wrote: > On Wed, 5 Feb 2014, Sarah Sharp wrote: > > > On Wed, Feb 05, 2014 at 11:58:12AM +0000, David Laight wrote: > > > > The problem is that the ax88179_178a driver submits receive URBs that > > > cross 64k boundaries, and are not aligned (they start at an 0x40 boundary). > > > Receive USB frames can contain multiple ethernet frames, by default they > > > are 20kB (and sit in 24kB of memory). > > > > Perhaps you should add printks when a TRB is split on 64KB boundaries > > and see if the device drops packets around that time? > > This seems kind of puzzling. > > In theory, any URB that's more than 1 byte long can cross a 64-KB > boundary. I don't understand why this should cause problems for > xhci-hcd. Sure, the transfer has to be split into multiple TDs where > the boundary crossing occurs. But why would that be problematic? If we split a non-scatter gather URB into two TRBs because of the 64-KB boundary rule, and we have to put a link TRB in between them, that may violate the TD fragments rule for 1.0 hosts. So the debugging should really only trigger when there's a link TRB in between two TRBs on the bulk ring. Sarah Sharp -- 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
