On Fri, Jan 08, 2016 at 02:52:28AM +1030, Ron wrote: > On Thu, Jan 07, 2016 at 05:38:09PM +0200, Mathias Nyman wrote: > > Hi > > > > On 02.01.2016 08:32, Ron wrote: > > > > > >Hi, > > > > > >It appears the commit e210c422b6fdd2dc123bedc588f399aefd8bf9de > > >"xhci: don't finish a TD if we get a short transfer event mid TD" > > >is causing transfers larger than 16kB to be unreliable. > > > > > >If I limit transfers to be no larger than 16kB, then it also works as > > >expected in an XHCI port with an unmodified build of Linus' current > > >head (v4.4-rc7-76-g9c982e8), but transfers larger than that do not. > > >I see an alternating cycle of a successful transfer, followed by two > > >that will time out waiting in libusb (with a 5 second timeout set), > > >before getting another successful transfer and the cycle repeating. > > > > > >I can run more tests and dig into this deeper if the reason for it > > >isn't immediately obvious in hindsight. > > > > > > > Thanks for the info, > > I can't spot anything obvious, but my brain might still be in vacation mode. > > > > Could you reproduce it with the attached patch, it only adds extra debugging? > > > > We should either see no output, or the following sequence: > > > > 1. "mid bulk/intr SP, wait for last TRB event" > > 2. "last trb has length set" > > 3. "and last trb is SHORT_TX, OK" > > > I guess one out of 3 ain't good ... all I see logged is: > > [ 60.015708] xhci_hcd 0000:04:00.0: mid bulk/intr SP, wait for last TRB event > [ 65.017374] xhci_hcd 0000:04:00.0: mid bulk/intr SP, wait for last TRB event > [ 70.455451] xhci_hcd 0000:04:00.0: mid bulk/intr SP, wait for last TRB event > [ 75.456248] xhci_hcd 0000:04:00.0: mid bulk/intr SP, wait for last TRB event > > I'm passing 5 seconds to libusb as the requested timeout. And if I limit the maximum transfer size to 16kB (the above was with 64kB transfers), then I see nothing logged at all. So if that code does indeed look sane, perhaps the issue is really in the code that's splitting large transfers doing something funny? Ron -- 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
