Re: [RFC 0/4] add master channel switch announcement support

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

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Hey,

On Tue, May 14, 2013 at 11:27:34AM +0200, Simon Wunderlich wrote:
> > > [....]
> > 
> > I don't really like your approach of building all the IEs in the kernel.
> > There are some things, like the country-after-switch in the CSA wrapper
> > (introduced in 11ac), that would be really awkward this way.
> 
> Hmm ... OK. I have not checked 802.11ac yet (actually I don't have access to the
> drafts anyway). So what we have to expect is changing the country after the switch,
> or also other new things?
> 
> > >  * We already have NL80211_CMD_CH_SWITCH_NOTIFY which is only used for notification.
> > >    Maybe we can rename that and re-use it instead of adding a new command
> > >    NL80211_CMD_CHANNEL_SWITCH?
> > 
> > Sure, I don't really care though.
> > 
> OK, will try to merge that then. Seems cleaner than having multiple channel switch
> commands in the API.
> 
> > >  * could other drivers (next to ath9k) work with this API?
> > 
> > Probably not easily. Any TI folks reading this?
> 
> I was thinking about adding another callback function or option for that for drivers
> who do the channel switch internally. Then we would only need mac80211 to adapt.
> 
> Would that help, or what would be problematic?
> > 
> > 
> > Anyway I think it'd be better to try to provide
> >  (a) the "during-switch IEs", maybe with an offset to the counter so
> > mac80211,
> >      driver or the device itself can count down
> >  (b) the "after-switch beacon" IEs (and maybe probe response for
> o> offload)
> 
> Yeah, that would be an alternative. I've been inspired by IEEE 802.11-2012/6.3.17
> (MLME-CHANNELSWITCH) originally. :)
> I think your suggestion is good for AP where we control the beacon. For IBSS it
> would be a little different: when a channel switch is triggered, userspace does
> not know the beacon (and will not set it). Therefore, we could only accept the
> change IEs and skip the "after-switch-beacon" IEs (these would be re-generated
> internally) in IBSS mode. I guess it would be similar for mesh.
> 
> What do you think?

I'd like to bump this issue again - if we agree on that this solution could work
for IBSS and possibly other modes I'd like to prepare the patchset implementing that.
This is required for IBSS-DFS later after all ...

Thanks,
	Simon

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