Message-ID: <4BE257CC.7030308@free.fr>
Date: Thu, 06 May 2010 07:46:52 +0200
From: Benoit Papillault <benoit.papillault@free.fr>
MIME-Version: 1.0
To: Johannes Berg <johannes@sipsolutions.net>
CC: John Linville <linville@tuxdriver.com>,
	linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v2] cfg80211/mac80211: better channel handling
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Le 06/05/2010 07:35, Johannes Berg a écrit :
> On Wed, 2010-05-05 at 22:58 +0200, Benoit Papillault wrote:
>
>> Real hardware are not capable of listening on multiple channels (except
>> 2 ht20 channels in ht40 mode, maybe?). So I don't understand why we
>> should have a per-interface channel.
>>
>> I think we should either have two strategies :
>>
>> - "first one is the winner" : once a channel has been set, it cannot be
>> changed. For instance, if you create an AP interface (with hostapd) and
>> latter a STA interface, the STA interface can only scan on the channel
>> the AP is.
>
> That's what you get now.
>
>> - "last one is the winner" : in this case, the last call to set the
>> channel is always successful. Of course, this will change channel on
>> existing interfaces which might change their IE accordingly, through an
>> appropriate API.
>
> That's pretty much impossible to implement with the current split
> between user and kernel space.
>
>> I might be wrong, but I don't see this multi-channel usage...
>
> Say you have two stations associated to two different APs. They can
> powersave while they are on the channel for the other AP. It'll be done,
> rather soon, trust me :)
>
> johannes

I understand now and I am impressed as well! I don't know how this could 
work in the details, but I trust you on this :-)

Regards,
Benoit