RE: usb: gadget: f_fs: O_NONBLOCK waits MAX_SCHEDULE_TIMEOUT

[Peter Chen]

> >>>>
> >>>> Thank you, that sounds like the best approach.
> >>>> In this case I think perhaps the long wait without any data is an
> >>>> problem with the imx6 Chipidea USB controller.
> >>>
> >>> What's the possible problem?
> >>
> >> Sorry for the delay in replying, I have been getting some more
> >> details with a USB Analyser.
> >>
> >> The scenario is that the NCM  device is enumerating so we see the
> messages to:
> >>
> >> SetAddress (1)
> >> GetDescriptor (Device)
> >> GetDescriptor (StringN)
> >> GetDescriptor (Configuration)
> >> SetConfiguration (1)
> >> GetDescriptor (String iInterface)
> >> GetDescriptor (String iInterface)
> >>
> >> At this point the NCM host sends Writes to the F_FS EP0 but for some
> >> reason the host device does not respond and only issues SOF packets
> >> for hours. This happens occasionally and is fixed by turning the device off
> and on again.
> >>
> >>
> >
> > We may find this 'some reason', is it device error or host error?
> >
> > Do you have below patch in your code:
> >
> > commit 953c66469735aed8d2ada639a72b150f01dae605
> > Author: Abbas Raza <Abbas_Raza@xxxxxxxxxx>
> > Date:   Thu Jul 17 19:34:31 2014 +0800
> >
> >     usb: chipidea: udc: Disable auto ZLP generation on ep0
> >
> >     There are 2 methods for ZLP (zero-length packet) generation:
> >     1) In software
> >     2) Automatic generation by device controller
> >
> >     1) is implemented in UDC driver and it attaches ZLP to IN packet if
> >        descriptor->size < wLength
> >     2) can be enabled/disabled by setting ZLT bit in the QH
> >
> > Peter
> 
> Yes I have that patch, could that be a problem?
> 

No, you need that patch.
Get to know which side has problem first.

Peter

> Jim
> 
> >
> >> Unless I am mistaken from a NCM gadget point of view the attached
> >> device is working correctly and there is no way to know it has failed, is that
> correct?
> >>
> >>>
> >>>>
> >>>> I guess it should suspend and drop the connections if there is no
> >>>> traffic for more than 10ms?
> >>>>
> >>>
> >>> If the Device side NAK host's IN/OUT token continually, the pipe
> >>> will not be stopped, the host will send token continually until the
> >>> application cancel this request.
> >>>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/