If after applying the patch I still get the warning and the scanner still isn't
working - did I do something wrong?
cat /proc/version is telling me I'm running the kernel I have compiled.
Thanks a lot,
and
Kind regards,
Gunter.
On 15.09.2014 21:50, Alan Stern wrote:
> On Mon, 15 Sep 2014, Mathias Nyman wrote:
>
> > I haven't had time to dig into the usbmon traces, but I just got another
> > report from Gunter K�ningsmann about similar scanner problem, and I just
> > noticed
> > that in both cases we round the interval for high speed bulk _IN_ endpoint,
> > which should not have interval set at all.
> > The interval value should be ignored by host, but maybe setting it still
> > could cause some issues.
> >
> > I don't have high hopes for this patch, but it's worth a shot.
> > Can you try this out and see if it makes any difference?
> >
> > -Mathias
> >
> > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> > index 8936211..7f21b77 100644
> > --- a/drivers/usb/host/xhci-mem.c
> > +++ b/drivers/usb/host/xhci-mem.c
> > @@ -1291,7 +1291,8 @@ static unsigned int xhci_get_endpoint_interval(struct
> > usb_device *udev,
> > /* Max NAK rate */
> > if (usb_endpoint_xfer_control(&ep->desc) ||
> > usb_endpoint_xfer_bulk(&ep->desc)) {
> > - interval = xhci_parse_microframe_interval(udev, ep);
> > + if (!usb_endpoint_dir_in(&ep->desc))
> > + interval =
> > xhci_parse_microframe_interval(udev, ep);
>
> It's not a good idea to test the direction of control endpoints, since
> they are bi-directional.
>
> Also, xhci_parse_microframe_interval assumes the value is stored with
> an exponential encoding, but the NAK rate value for control and
> bulk-OUT endpoints is stored in the endpoint descriptor directly as a
> number of microframes (not exponential).
>
> It's not fully clear how xHCI controllers use the Interval field in the
> Endpoint Context. Table 65 notably fails to include a line for HS
> bulk-OUT/control endpoints, and the text isn't clear as to whether the
> field is interpreted using exponential coding for non-periodic
> endpoints. As near as I can tell, it is -- which means you should call
> xhci_microframes_to_exponent() here, not
> xhci_parse_microframe_interval().
>
> Alan Stern
>
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