Subject: Re: [PATCH] mac80211: Push idle state to driver before stop
From: Johannes Berg <johannes@sipsolutions.net>
To: Paul Stewart <pstew@google.com>
Cc: linux-wireless@vger.kernel.org, luis.rodriguez@atheros.com
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Date: Thu, 16 Dec 2010 13:04:07 +0100
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On Thu, 2010-12-16 at 03:51 -0800, Paul Stewart wrote:

> So, I'm trying to balance two fairly nasty problems here.  On one end
> we have the problem before any changes where the device is not shut
> down when it legitimately should be -- we ifdown the device while scanning
> but the device in ath9k is not set to "idle".

See, I contend that statement -- we actually *turn off* the device with
stop(), so it shouldn't matter.

> Fixing the problem in ath9k
> alone causes a separate problem.  If you stop the driver from mac80211's
> pm.c, ath9k would set the device ps_idle, when mac80211 does not
> consider the device to to be idle.  Thus, when we resume from suspend,
> the device stays quiescent (mac80211 has no reason to believe it needs
> to do anything special to be able to tx, receive beacons, etc.)

How so? After resume, mac80211 will invoke start(), add interfaces and
stations back, and then invoke drv_config with all flags in "changed"
set. Therefore, at this point, the device should be reset. Where's this
not working?

I think the problem might be that ath9k is expecting mac80211 to
perfectly nest calls to idle/non-idle, even across suspend/resume and
device shutdown. I don't think that's feasible at all.

johannes