On Fri, 7 Feb 2014, Devin Heitmueller wrote: > Hi Alan, > > Thanks for taking the time to respond. > > On Thu, Feb 6, 2014 at 5:08 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > Is it possible to get any debugging information from the machines in > > the field? > > At this point all I know is the usb_submit_urb() is returning -EBIGF. > In the 3.7 ehci_hcd driver that can come from one of three places and > I'm in the process of deploying some additional logging so at least I > know which of those three is causing it. I do know that when it > occurs, it's not necessarily at the start of streaming (i.e. it's not > some sort of initial bandwidth reservation issue). I see it happening > when the URBs are being actively serviced by the completion handler > and resubmitted. I remember seeing errors like that. It was a while ago, and I can't remember exactly what the cause turned out to be. Or the fix... There were several changes to the isochronous scheduling code in ehci-hcd before it finally settled down. > > I can point out that in the last one or two kernel releases there were > > significant changes to the snd-usb-audio driver that affect the way it > > interacts with ehci-hcd. Just to make your life more difficult... > > Supposedly they never had this issue in 2.6.33, so presumably it's > some sort of regression in either the EHCI driver or snd-usb-audio > between 2.6.33 and 3.7. That said, I'm hoping it's something already > fixed in 3.13 and I just need to find the right change to backport. > > I know the ISO_ASAP behavior changed, but aside from that do you see > any reason that I wouldn't be able to backport the entire > snd-usb-audio driver from 3.13 (leaving the ehci driver at the 3.7 > level)? As I recall, there were only two changes to snd-usb-audio that were relevant for this problem: commits 57e6dae1087b and 976b6c064a95. Of course, you may need to include other commits before these will apply cleanly. If you're willing to make these changes to one or two of the subsystems, why not go all the way up to a 3.12 or 3.13 kernel? Alan Stern -- 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
