From: James Cameron <quozl@laptop.org>
To: Bing Zhao <bzhao@marvell.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [RFC] mwifiex: block work queue while suspended
Date: Wed, 28 May 2014 14:49:45 +1000 [thread overview]
Message-ID: <20140528044945.GI4151@us.netrek.org> (raw)
In-Reply-To: <477F20668A386D41ADCC57781B1F70430F70F5E4B3@SC-VEXCH1.marvell.com>
On Tue, May 27, 2014 at 09:35:21PM -0700, Bing Zhao wrote:
> Hi James,
>
> > > > We use a GPIO to wake from WLAN.
> > >
> > > This doesn't match the gpio parameter configured in hscfg command
> > > 0xe5.
> >
> > You're right, and I'm quite wrong. Sorry about that. I misread our
> > code.
> >
> > Correction, we use SDIO to wake from WLAN.
> >
> > We set gap to 0xff, which we think is a special value that means the
> > device will wait for the host to acknowledge before sending data to
> > the host.
>
> Yes, gap=0xff should be used. Actually I also have the patch to set
> gap to 0xff queued in my local tree. I will send it upstream.
Thanks. Today I have been testing with gap 50ms and no longer able to
reproduce the "mmc0: Timeout waiting for hardware interrupt." problem.
> > Looking through history of development, we thought that this would
> > avoid a race condition, where the host starts to suspend, configures
> > the device for host sleep, but the device may wake in the time before
> > the host suspends.
> >
> > We don't see this "mmc0: Timeout waiting for hardware interrupt."
> > problem unless we use WPA2. It does not reproduce on an open access
> > point.
>
> With WPA2 enabled, does the "mmc0 timeout" happen in every suspend
> attempt?
No, it is rare, of the order of one in every 6000 attempts, and depends
on the timing of arriving packets. Our reproducer uses a ping ramp,
with interval varying from 0.1 to 0.9 seconds with 50ms increment, and
this brings the problem frequency down to about one in 200 attempts.
The OLPC XO-4 by default tries to suspend automatically when user is
idle, which is why we notice the problem.
--
James Cameron
http://quozl.linux.org.au/
next prev parent reply other threads:[~2014-05-28 4:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 1:24 [RFC] mwifiex: block work queue while suspended James Cameron
2014-05-22 3:50 ` Bing Zhao
2014-05-22 5:46 ` James Cameron
2014-05-23 4:12 ` Bing Zhao
2014-05-26 8:01 ` James Cameron
2014-05-27 23:39 ` Bing Zhao
2014-05-28 2:01 ` James Cameron
2014-05-28 4:35 ` Bing Zhao
2014-05-28 4:49 ` James Cameron [this message]
2014-05-28 5:04 ` Bing Zhao
2014-05-29 1:22 ` James Cameron
2014-05-29 2:10 ` Bing Zhao
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