Re: [PATCH 5/7] mac80211: Expand powersave configuration flag to be two bits

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2013-02-06 at 12:02 -0600, Seth Forshee wrote:

> > Ah, wl1251 is the weird thing that wants to be told when to wake up/go
> > to sleep, and then sends nulldata packets itself ... so when we send
> > nulldata packets *again* for off-channel, because it also uses software
> > scanning. Like I said before -- "stupidest powersave implementation on
> > the planet".
> 
> Ah, I had wondered what hardware that code was there for :-)

I was actually wrong -- wl1251 has HW scan so it doesn't matter.
However, iwlegacy does this...

> So I think the approach I'm advocating could possibly make things better
> for wl1251. If it's told about going to off-channel powersave rather
> than being told it's leaving powersave, maybe it can do the right thing
> with the nullfunc frames without mac80211 generating the extra nullfunc.
> I don't know that for sure though because I don't understand how the
> hardware works.

Probably not. For iwlegacy anyway it won't help.

> > > So using these definition powersave is already a mandatory feature for
> > > any hardware which uses software scanning. 
> > 
> > Even offloaded scanning, it's just not visible to mac80211 then.
> 
> Okay, sure. I'm just thinking of things from the mac80211 perspective.

Right, sure.

> > > All I'm really doing is
> > > making this explicit, and drivers would now opt in to being placed into
> > > the doze state rather than opting into powersave in general. And of
> > > course drivers are now told about transitions to the non-doze powersave
> > > state (what I'm calling offchannel), so that drivers which need to do
> > > hardware configuration for this state can do so.
> > 
> > Ok, so maybe just calling it offchannel makes more sense, although that
> > really interacts only this way with powersave in managed mode, in P2P GO
> > mode .... oh well.
> 
> I admit I've only been considering managed mode and know next to nothing
> about P2P GO mode. If I'm creating problems for any other modes I'd
> definitely like to know about it so I can take it into consideration.

No no, I'm just saying there "powersave" could have even more
meanings ...

johannes