Subject: Re: Thoughts about mac80211 client PS implementation
From: Johannes Berg <johannes@sipsolutions.net>
To: Kalle Valo <kalle.valo@nokia.com>
Cc: linux-wireless@vger.kernel.org
In-Reply-To: <87k5bhkjf1.fsf@nokia.com> (sfid-20081105_212743_302957_1CBD059B)
References: <87k5bhkjf1.fsf@nokia.com>
	 (sfid-20081105_212743_302957_1CBD059B)
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Date: Wed, 05 Nov 2008 21:33:55 +0100
Message-Id: <1225917235.3619.180.camel@johannes.berg> (sfid-20081105_213356_947992_EEBE585B)
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On Wed, 2008-11-05 at 22:27 +0200, Kalle Valo wrote:
> I'm working on implementing the "dynamic Power Save" (ie. PS enabled
> after an idle period) feature to mac80211. Here are my current
> thoughts:
>=20
> First of all, I think we should enable CONF_PS only when associated.
> So instead of directly calling hw_config() from
> ieee80211_ioctl_siwpower() we should do that only when associated.
> Otherwise we change it only after association or disassociation. This
> means that we have to add a separate bit/variable for storing what
> user has requested.

Totally agreed.

> PS should be disabled while associated and running software scan, and
> naturally re-enabled after the scan has finished. I assume hardware
> scanning implementations are clever enough to disable PS when scanning
> and we don't have to worry about that case.

And on that too. And should there be a monitor flag that disables PS, so
that we can "refcount" the PS bit in a way?

> The dynamic PS implementation is still a bit open issue for me. I have
> been thinking something like that in tx.c frames will be queued if PS
> is enabled, PS will be disabled in a workqueue by calling
> ieee80211_hw_config() and only after that the queued frames are
> transfered. So something similar as sta->ps_tx_buf does in AP mode. No
> idea if this is feasible or not.

Not sure I understand the dynamic PS yet. Why would you queue up frames?
To reduce the number of radio wakeups when TX traffic is low?

johannes

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