Support for scan while in AP mode, and offchannel while in AP mode

Michal Kazior michal.kazior at
Mon Aug 18 23:24:03 PDT 2014

On 19 August 2014 08:07, Kalle Valo <kvalo at> wrote:
> Avery Pennarun <apenwarr at> writes:
>>>> Are there any plans to implement this feature?  It's important in
>>>> order to implement automatic channel change in case of changes in the
>>>> interference environment.
>>> No plans at the moment. Does anyone know how much work would it be to
>>> change mac80211 to support this with hw_scan?
>> Is there any particular reason it can't just resort to a sw_scan for
>> this use case?  What's the benefit of hw_scan?  I'm surprised there
>> would be any particular CPU time taken for such a thing.
> For mobile devices hw_scan is important because the ability to allow the
> host CPU to sleep while scanning. For others I'm not that sure, maybe
> firmware can do timing better (less intrusive) than host based sw
> scanning?

sw_scan requires a driver to be able to "just change the channel".
Some device firmwares have no direct control over programmed hw
channel. Instead they have start/join/connect commands that implicitly
setup hw channel. ath10k is actually like that, isn't it (vdev start)?


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