Re: [Greenmesh] [ath9k] mesh powersave hardware sleep + wakeup

[Marco Porsch <marco.porsch@etit.tu-chemnitz.de>]

On 04/12/12 06:05, Johannes Berg wrote:
> On Wed, 2012-04-11 at 13:00 +0200, Marco Porsch wrote:
>
>> Thus, I think we will need an additional/extended interface
>> mac80211<->driver here.
>>
>> I see two possibilities:
>> a) request the next wakeup time from mac80211 each time the hardware is
>> put to sleep (e.g. from ath9k_ps_restore).
>> b) give a whole list of periodic wakeup events of all vif to the driver.
>> Then the driver is supposed to sort out the closest event.
>>
>> What would be the better approach for such an interface? Or maybe a
>> completely different idea?
>
> What time units would that be in, and how could you correlate them?

I did not take an exhaustive overview over all possible drivers.
But as the current mac80211<->driver interface carries only beacon 
interval (in TU) and DTIM period, that should be a good starting point.
ath9k additionally relies on the neighbors address to check whether it 
can resume sleep after receiving an expected beacon (see setting of 
'is_mybeacon' in ath_rx_tasklet).

Concerning correlation, in mesh mode we recently have t_offset (in TSF 
increments) stored in sta_info and in client mode the drivers' 
synchronised TSF should be the reference (but I am not quite sure what 
happens when one client is associated to multiple AP).

Regards,
Marco