Re: usb: gadget: f_fs: O_NONBLOCK waits MAX_SCHEDULE_TIMEOUT

From: Peter Chen
Date: Wed Apr 01 2015 - 20:25:40 EST

On Wed, Apr 01, 2015 at 06:29:05PM +0100, Baxter, Jim wrote:
> >
> > FunctionFS is very specific, because read/write operations are directly
> > translated into USB requests, which are asynchronous, so you cannot use
> >
> > If you need non-blocking API you can use Asynchronous I/O (AIO). You can
> > find some examples in kernel sources (tools/usb/ffs-aio-example/).
> >
> > Br,
> > Robert Baldyga
> >
> 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?

> 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.


Best Regards,
Peter Chen
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