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Date: Thu, 20 Feb 2014 10:31:33 +0100
Message-ID: <CALhHN=q2Dw+wNraY=F6ZHSrcv1esseQNJn9m+TV0KR-ZAhs5iw@mail.gmail.com> (sfid-20140220_103143_076524_FA993803)
Subject: Re: [PATCH] crda: handle AUTO bw setting in db2rd
From: Janusz Dziedzic <janusz.dziedzic@tieto.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>,
	Janusz Dziedzic <janusz.dziedzic@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"John W. Linville" <linville@tuxdriver.com>
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-wireless-owner@vger.kernel.org

On 20 February 2014 09:03, Janusz Dziedzic <janusz.dziedzic@tieto.com> wrote:
> On 20 February 2014 08:59, Johannes Berg <johannes@sipsolutions.net> wrote:
>> On Thu, 2014-02-20 at 08:57 +0100, Janusz Dziedzic wrote:
>>
>>> >> Yes, seems we should send this even this is 0.
>>> >> Next for old kernel, all channels where BW=0 will be HT20 only.
>>> >
>>> > Is that really a good idea?
>>> >
>>> > Maybe crda should just get the logic to determine maximum bandwidth,
>>> > like you did in the kernel, and then we can even revert the kernel code
>>> > again?
>>> >
>>> Yes, this is possible to calculate this in crda (or even set this manually).
>>
>> Ok. Would that help older kernels? How would we handle genregdb.awk?
>>
> In case of older kernels we will fail (end_freq - start_freq < bw) with -EINVAL.
> So, bw=0 (cfg calculation) seems like best idea - will work with new
> and old kernels.
>
Seems cfg80211 max bandwidth calculation is best option here.

We should set BW as is in old regulatory (skip this BW=0 patches) -
will work fine with old kernels.
And in new regulatory add RULE flag NL80211_RRF_AUTO_BW, which will be
checked in newer kernels and if AUTO_BW flag we will skip (end_freq -
start_freq < bw) check and calculate maximum available bandwidth. What
you think?

BR
Janusz
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