From: Peter Chen <peter.chen@freescale.com>
To: "Baxter, Jim" <jim_baxter@mentor.com>
Cc: Robert Baldyga <r.baldyga@samsung.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"Zapolskiy, Vladimir" <Vladimir_Zapolskiy@mentor.com>,
"balbi@ti.com" <balbi@ti.com>
Subject: Re: usb: gadget: f_fs: O_NONBLOCK waits MAX_SCHEDULE_TIMEOUT
Date: Thu, 2 Apr 2015 08:23:49 +0800 [thread overview]
Message-ID: <20150402002348.GA10964@shlinux2> (raw)
In-Reply-To: <551C2AE1.9000608@mentor.com>
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
> > O_NONBLOCK.
> >
> > 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
next prev parent reply other threads:[~2015-04-02 0:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-31 18:53 usb: gadget: f_fs: O_NONBLOCK waits MAX_SCHEDULE_TIMEOUT Baxter, Jim
2015-03-31 20:28 ` Felipe Balbi
2015-04-01 8:06 ` Robert Baldyga
2015-04-01 17:29 ` Baxter, Jim
2015-04-02 0:23 ` Peter Chen [this message]
2015-05-22 11:12 ` Baxter, Jim
2015-05-25 1:55 ` Peter Chen
2015-06-01 16:25 ` Baxter, Jim
2015-06-02 3:01 ` Peter Chen
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