Re: [PATCH v4 5/6] nl80211/cfg80211: add ap channel switch command

[Johannes Berg <johannes@sipsolutions.net>]

On Thu, 2012-11-01 at 09:54 +0200, Victor Goldenshtein wrote:

> > This however introduces a new problem. Let's suppose we have 2 APs on
> > channel 1. The device doesn't support multi-channel. We won't be able to
> > switch channel on these APs at all.
> >
> > We might want to change the channel switch to resolve around the channel
> > itself (not the interface) - so we'd be saying "move all interfaces with
> > channel X to channel Y" instead of "move interface X to channel Y".
> >
> > Or we could let the driver decide what it'll do - e.g. silently switch
> > more than one interface to a different channel (which makes sense with
> > AP/DFS I guess) and just notify cfg/userspace about it. That would
> > require us to provide a way to switch interfaces (atomically possibly)
> > between channels while keeping in sync with interface combinations though.
> >
> 
> If the driver/device supports MR only on a SC - means it doesn't 

What's MR? SC = single channel?

> supports channel switch in MR, so basically the radar detection event 
> triggers AP channel switch which fails (with this new check) and the AP 
> shut down.

But I was speaking of two interfaces on a single channel.

> Of course there are possible driver specific workarounds (as you 
> mentioned above) but these are not part of this series.

yeah but you should probably allow for some strategy of handling this?

> Just for interest's sake, what is the use case having two APs on the 
> same channel?

Umm, lots of things? P2P groups, multiple BSSIDs, ...

johannes