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Date:   Fri, 9 Aug 2019 15:50:25 -0500
From:   Seth Forshee <seth.forshee@canonical.com>
To:     Chen-Yu Tsai <wens@kernel.org>
Cc:     Chen-Yu Tsai <wens@csie.org>, wireless-regdb@lists.infradead.org,
        linux-wireless@vger.kernel.org
Subject: Re: [PATCH] wireless-regdb: Extend 5470-5725 MHz range to 5730 MHz
 for Taiwan (TW)
Message-ID: <20190809205025.GP10402@ubuntu-xps13>
References: <20190726030538.16784-1-wens@kernel.org>
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On Fri, Jul 26, 2019 at 11:05:38AM +0800, Chen-Yu Tsai wrote:
> From: Chen-Yu Tsai <wens@csie.org>
> 
> This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
> The Linux kernel however does not seem capable of considering them
> most restrictive subset of multiple rules.
> 
> Since 5725 ~ 5730 MHz belongs to the next range which has looser
> requirements, we can do this manually and extend the range by 5 MHz
> to make the kernel happy and be able to use channel 144.
> 
> Also, looking at the US regulations, which the TW ones are based on,
> The DFS range ends at 5730 MHz, while the next range starts at 5735
> MHz. This doesn't match the actual regulations, but is skewed to meet
> wireless channel boundaries. I prefer the database match the law,
> and be adjuested only if necessary.
> 
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> ---
> 
> I have a vague impression that you asked about the range boundaries
> when I first updated the rules for Taiwan. And here we are again.

I don't recall, but I too prefer that we keep the boundaries mostly in
line with the regulations, not the wireless channel boundaries. Here it
does seem appropriate though to borrow the extra 5MHz into a more
rescrictive rule.

I wasn't sure about having rules with overlapping ranges. I've been
looking at the code though, and I don't see that it will be an issue. I
may give a few more days though to see if anyone else knows some reason
I missed that it could be a problem.

Thanks,
Seth

> 
> ---
>  db.txt | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/db.txt b/db.txt
> index 37393e6..2e149b6 100644
> --- a/db.txt
> +++ b/db.txt
> @@ -1249,7 +1249,11 @@ country TW: DFS-FCC
>  	# 5.15 ~ 5.25 GHz: 30 dBm for master mode, 23 dBm for clients
>  	(5150 - 5250 @ 80), (23), AUTO-BW
>  	(5250 - 5350 @ 80), (23), DFS, AUTO-BW
> -	(5470 - 5725 @ 160), (23), DFS
> +	# This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
> +	# Since 5725 ~ 5730 MHz belongs to the next range which has looser
> +	# requirements, we can extend the range by 5 MHz to make the kernel
> +	# happy and be able to use channel 144.
> +	(5470 - 5730 @ 160), (23), DFS
>  	(5725 - 5850 @ 80), (30)
>  	# 60g band, LP0002 section 3.13.1.1 (3)(C), EIRP=40dBm(43dBm peak)
>  	(57000 - 66000 @ 2160), (40)
> -- 
> 2.20.1
>