On Wed, 2011-02-02 at 11:22 -0800, Ben Greear wrote:
> > Based on the powersave comments I had earlier, maybe we should remove
> > that bit for now? Work items here require powersave is disabled, but we
> > won't do that right now if we're on the same channel.
>
> The problem is, if we leave the work_work() in the original
> manner, the on/off channel state changes are not properly
> tracked because work blindly assumes it goes off/on channel.
> This breaks assumptions about when we must call the return-to-channel
> logic. I think if we do not religiously track the on/off channel
> state changes it would be too easy to get in a state where we think
> we are on-channel but haven't actually re-enabled xmit queues, etc.
But if we pretend all work is off-channel, won't it be OK to return from
off-channel, even if it isn't really another channel?
> I think I would rather change the work logic to expressly disable/enable
> powersave. That wouldn't be difficult, would it?
Probably not -- but the code you modified regarding powersave probably
needs adjustment then.
> I don't think it does anything if we are scanning on-channel
> with my patch.
> The enable/disable logic is now in the offchannel code...
>
> Do we need to disable it if we are scanning on channel? If so,
> I can add that explicitly to the scanning code.
Yes, I think we do need to do that, since otherwise we won't actually
receive any beacons other than from our own AP.
> While we are on that topic, it seems the conf.flags are set
> opposite to what I expect. Is that code below correct?
I think so.
> /* inform AP that we are awake again, unless power save is enabled */
When we return from scanning, we're awake, but the AP thinks we're
asleep.
> static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
> {
> struct ieee80211_local *local = sdata->local;
>
> if (!local->ps_sdata)
> ieee80211_send_nullfunc(local, sdata, 0);
So in the case we shouldn't go to sleep we just tell the AP that we woke
up again.
> else if (local->offchannel_ps_enabled) {
> /*
> * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
> * will send a nullfunc frame with the powersave bit set
> * even though the AP already knows that we are sleeping.
> * This could be avoided by sending a null frame with power
> * save bit disabled before enabling the power save, but
> * this doesn't gain anything.
> *
> * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
> * to send a nullfunc frame because AP already knows that
> * we are sleeping, let's just enable power save mode in
> * hardware.
> */
> local->hw.conf.flags |= IEEE80211_CONF_PS;
And in the other case we really go to sleep.
johannes
johannes
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