Re: multicast traffic and ath9k

[Christian Lamparter <chunkeey@web.de>]

On Friday 09 January 2009 14:59:25 Vivek Natarajan wrote:
> 
> Johannes Berg wrote:
> 
> > > Is the mc bit
> > > checking done only on enabling power save? if set and mc packets are received,
> > > how does it automatically go back to sleep and wouldn't there be any conflict
> > > between mac80211 and the hw regarding power state since mac80211 is not aware
> > > of the mc bit induced state change?
> 
> > I don't think there would be a conflict. mac80211's CONF_PS is always
> > only "go to sleep if you can", so receiving multicast traffic would
> > obviously imply not being able to go to sleep. When mac80211 then unsets
> > the CONF_PS flag you'd just not go back to sleep after being awake for
> > MC traffic.
> 
> How does the mac80211 know if the hw is receiving mc traffic or not and
> unset the CONF_PS flag accordingly? Am I missing something basic here?
> 
> Maybe p54 (stlc45xx) has the answer for how it goes back to sleep after mc traffic.

Well we have a flag to tell the firmware to do the following thing in client mode (while sleeping)

"If the PSM object's *_PSM_MCBC flag is set, and a beacon is received with the TIM's multicast traffic bit
set, [...] or the LMAC stays awake until the TIM's multicast traffic bit is cleared again from the beacon".

see:
STSW45X0C LMAC API: page 24 - LM_PSM_MCBC (~ P54_PSM_MCBC)

Regards,
	Chr