On Fri, 14 Oct 2016, Benjamin Staton wrote: > Brian, > > Working - I appreciate this. I applied this mini-patch to kernel > 4.8.1 and confirm that after a few test scans, I now have no problem > with the USB Canon scanner. > > Also seems to have cleared up a puzzling no-input problem I was having > with a cheap no-brand USB keyboard/video/mouse switch under 4.8.1. > > Thanks, > > Joe > > On Fri, Oct 14, 2016 at 3:52 PM, Bryan Paluch <bryanpaluch@xxxxxxxxx> wrote: > > I've been experiencing similar issues with usb audio headsets. There is an > > issue for ubuntu 16.10 here > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1630063 . > > > > I was able to fix the issue by changing the IO_WATCHDOG_DELAY in ohci-hcd.c > > from 250 msec to 275 msec. I suspect that the new timer wheel based timers > > in 4.8 have exposed a bug in the ohci driver. Before the io watchdog timer > > was set to 250 with 20 msecs of slack time. This is more than likely just a > > hacky work around but I'm able to use my usb headphones now. Here's my diff It's not a bug in the ohci-hcd driver; it's a workaround for bugs in the hardware of certain OHCI controllers. The driver checks for an action that the controller is supposed to carry out after a delay no longer than 8 ms! If it turns out that the hardware actually takes somewhere between 250 and 275 ms to carry out this action, I'll be happy to increase the timeout value. > > diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c > > index 1700908..86612ac 100644 > > --- a/drivers/usb/host/ohci-hcd.c > > +++ b/drivers/usb/host/ohci-hcd.c > > @@ -72,7 +72,7 @@ > > static const char hcd_name [] = "ohci_hcd"; > > > > #define STATECHANGE_DELAY msecs_to_jiffies(300) > > -#define IO_WATCHDOG_DELAY msecs_to_jiffies(250) > > +#define IO_WATCHDOG_DELAY msecs_to_jiffies(275) > > > > #include "ohci.h" > > #include "pci-quirks.h" Bryan, if you submit this patch (following the instructions in Documentation/SubmittingPatches), I'll merge it into the kernel. Or if you prefer not to, I can submit the patch myself, giving you the appropriate credit. 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
