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Subject: Re: [RFC 0/7] add a KHz component to wireless channels
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>
References: <20200401062150.3324-1-thomas@adapt-ip.com>
 <1fb3634babea0a8bd0021493919d3ebd0e279087.camel@sipsolutions.net>
From:   Thomas Pedersen <thomas@adapt-ip.com>
Message-ID: <03b79029-c168-06df-2d8e-ef4179bd9ba2@adapt-ip.com>
Date:   Wed, 1 Apr 2020 11:26:56 -0700
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On 4/1/20 12:15 AM, Johannes Berg wrote:
> On Tue, 2020-03-31 at 23:21 -0700, Thomas Pedersen wrote:
> 
>> Some cfg80211 and nl80211 internals have been converted to handle units
>> of KHz, which is not unprecedented (net/wireless/reg.c), and the
>> collateral damage is localized.
> 
> :)
> 
>> One thing which is still unclear is backward compatibility in nl80211.
>> If a frequency offset is supplied to an older kernel, it'll just
>> silently fail to do the right thing.
> 
> But will it? It mostly requires to have a struct ieee80211_channel
> registered with the wiphy for a given frequency, and won't find that?

I was worried the wrong ("rounded down") channel would be found, but I
think the point is mostly moot since that channel wouldn't exist either.

> But speaking of which - I was expecting to see a new *band* here for
> S1G, so that you can actually register the channels properly in the
> wiphy struct? Or is that just not part of this patchset yet?

Yeah just trying to focus on the frequency offset stuff and keep S1G out
of it for now. Do you think it would be helpful to cap it with the new
S1G band definition?

-- 
thomas