Re: [PATCH] mac80211: implement STA CSA for drivers using channel contexts

[Johannes Berg <johannes@sipsolutions.net>]

On Sun, 2013-08-25 at 16:14 +0300, Arik Nemtsov wrote:

> >> The right thing for chan_switch drivers would be not to call hw_config()..
> >
> > chan_switch? or chanctx?
> 
> both. the hw_config(channel) is meaningless for chanctx drivers. The
> legacy code for op_chan_switch drivers didn't call hw_config() as
> well, assuming they'd already get notified internally by their op.

Right.

> >> The TI driver implements the chan_switch op and uses channel contexts.
> >
> > Huh, ok, that was a combination I didn't think was going to exist, since
> > the chanswitch API doesn't really tell you what channel context etc.
> > OTOH, it does give you the vif so you have the chanctx implicitly.
> 
> Yep, it's good enough. The driver gets the chandef from the vif.

Ok, fair enough.

> >> Note that with the above, the channel_contexts + software chan-switch
> >> drivers will still need the kind of code that I wrote. So it would
> >> just lead to replicated code. Or maybe you meant something else?
> >
> > We have too many possibilities I guess ... I think for MVM I want the
> > disconnect, not the channel context change in software. You're taking
> > that possibility away, hence my suggestion of a new hardware flag for it
> > or so.
> 
> I was thinking it's equivalent to to AP case - currently mac80211 is
> the dictator and simply changes the chandef once the lower drv
> completes the switch.

Yeah but the driver in this case has a choice to not supported it.

> Anyway IMHO the simplest approach to handle all the legacy stuff +
> chanctx it to keep the current patch as is, and add a mac80211 HW flag
> to support it, keeping the deauth option as default.
> That's what I think you're suggesting?

Yeah, that sounds about right.

> >> Also, where would you put csa_active = true (if at all) for a STA
> >> interface? Unlike AP, the trigger here is mac80211 code. So putting it
> >> there seemed appropriate.
> >
> > Yeah, I was really just trying to say that current chanctx drivers need
> > not really expect a chanctx to change channel unless they implement CSA,
> > but that currently means AP-CSA - basically what I just said above with
> > taking away the possibility of doing the deauth instead.
> 
> Let's keep the csa_active as I've used it, and just do a deauth when
> the csa-support HW flag is not given?

Works for me - I wasn't particularly worried about the csa_active
handling per se, but rather what it implied about the calls and driver
support etc.

johannes