Message-ID: <03c1e278fdd880bf7409c0b1c03366178b765cda.camel@sipsolutions.net>
Subject: Re: Tx power for slave devices in ETSI DFS region
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>,
        "wireless-regdb@lists.infradead.org" 
        <wireless-regdb@lists.infradead.org>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Date:   Tue, 15 Jan 2019 14:45:46 +0100
In-Reply-To: <423eaa39-fc06-6a5a-a8fd-5e15d503dff5@quantenna.com> (sfid-20181211_033105_299408_08BD2B1C)
References: <423eaa39-fc06-6a5a-a8fd-5e15d503dff5@quantenna.com>
         (sfid-20181211_033105_299408_08BD2B1C)
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Hi Igor,

On Tue, 2018-12-11 at 02:30 +0000, Igor Mitsyanko wrote:
> Hello,
> 
> according to ETSI 
> https://www.etsi.org/deliver/etsi_en/301800_301899/301893/02.01.01_60/en_301893v020101p.pdf
> section 4.2.3.2.2, table 2
> Note 3 states:
>  >Slave devices without a Radar Interference Detection function shall 
>  >comply with the limits for the frequency range 5 250 MHz to 5 350 MHz.
> 
> And Tx power limits are defined as following:
> 5150 to 5350: 20 dbm
> 5470 to 5725: 27 dbm

> Which means that if STA device can not do radar detection, it must use 
> 20dbm Tx powers on all channels (can not use 27 dbm limit).
> 
> 
> Looking at regdb 
> https://git.kernel.org/pub/scm/linux/kernel/git/sforshee/wireless-regdb.git/tree/db.txt, 
> power limit for frequency range 5470 to 5725 is defined at 27 dbm.

I guess somebody misinterpreted the spec, or some countries are less
strict?

> Question is: does wireless core assumes that each device can do radar 
> detection in slave modes (eg acting as a STA) and it is enabled by 
> default? I couldn't find any logic in kernel which would limit 27 dbm 
> power to 20 for STA devices.

No, we shouldn't assume that it can do radar detection by itself ...

I guess we should have some code? Or just fix the regdb?

johannes