On Fri, 14 Oct 2016, Benjamin Staton wrote:
> 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.
> On Fri, Oct 14, 2016 at 3:52 PM, Bryan Paluch <bryanpal...@gmail.com> 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
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