linux-kernel - Re: [PATCH 2/2] cfg80211: Use 5MHz bandwidth by default when checking usable channels

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Date:	Mon, 23 Jun 2014 12:04:34 +0200
From:	Felix Fietkau <nbd@...nwrt.org>
To:	Johannes Berg <johannes@...solutions.net>
CC:	Rostislav Lisovy <lisovy@...il.com>,
	"John W. Linville" <linville@...driver.com>,
	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michal Sojka <sojkam1@....cvut.cz>, s.sander@...dsys.de,
	jan-niklas.meier@...kswagen.de,
	Rostislav Lisovy <rostislav.lisovy@....cvut.cz>
Subject: Re: [PATCH 2/2] cfg80211: Use 5MHz bandwidth by default when checking
 usable channels

On 2014-06-23 11:08, Johannes Berg wrote:
> On Sun, 2014-06-22 at 13:41 +0200, Felix Fietkau wrote:
>> On 2014-04-15 14:37, Rostislav Lisovy wrote:
>> > Current code checks if the 20MHz bandwidth is allowed for
>> > particular channel -- if it is not, the channel is disabled.
>> > Since we need to use 5/10 MHz channels, this code is modified in
>> > the way that the default bandwidth to check is 5MHz. If the
>> > maximum bandwidth allowed by the channel is smaller than 5MHz,
>> > the channel is disabled. Otherwise the channel is used and the
>> > flags are set according to the bandwidth allowed by the channel.
>> > 
>> > Signed-off-by: Rostislav Lisovy <rostislav.lisovy@....cvut.cz>
> 
>> This change causes a regression and needs to be reverted or fixed.
> 
> Noted, I've reverted it in mac80211.git.
> 
>> It leaves Channel 12 enabled for US regdomain and does not prevent
>> bringing up AP mode on it (IEEE80211_CHAN_NO_20MHZ does not get set).
> 
> I'm not sure this makes sense - CHAN_NO_20MHZ shouldn't get set on that
> channel? It should be disabled for other reasons for AP mode - e.g.
> NO_IR.
I was thinking it could be valid in AP mode for 5 MHz operation.

- Felix
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