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Date:   Fri, 4 Mar 2022 00:20:09 +0200
From:   Jouni Malinen <j@w1.fi>
To:     Lorenzo Bianconi <lorenzo@kernel.org>
Cc:     hostap@lists.infradead.org, linux-wireless@vger.kernel.org,
        nbd@nbd.name, ryder.lee@mediatek.com, evelyn.tsai@mediatek.com,
        lorenzo.bianconi@redhat.com
Subject: Re: [PATCH 8/9] DFS: switch to background radar channel if available
Message-ID: <20220303222009.GC33342@w1.fi>
References: <cover.1640014128.git.lorenzo@kernel.org>
 <ec706e090d7e44bcc9afd2f9789802f8c07e3c3f.1640014128.git.lorenzo@kernel.org>
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On Mon, Dec 20, 2021 at 04:48:23PM +0100, Lorenzo Bianconi wrote:
> On radar detection on the main chain switch to the channel monitored
> by the background chain if we have already performed the CAC there.

Is it clear that the channel on the background chain, if one is
available with CAC performed, comply with the ETSI uniform spreading
requirements? The comment below feels a bit misleading, but the way
patch 5/9 picks the channel for background CAC might be sufficient for
this. If so, it would be good to note that in the comment here:

> diff --git a/src/ap/dfs.c b/src/ap/dfs.c
> +hostapd_dfs_background_start_channel_switch(struct hostapd_iface *iface,

> +	/*
> +	 * If background radar detection is supported and radar channel
> +	 * monitored by background chain is available switch to it without
> +	 * waiting for the CAC otherwise let's keep a random channel.

That first part leaves it a bit open whether the random channel part from
the end of the sentence applies in practice for the new operating
channel. It is important to make this clearly describe the functionality
needed to meet uniform spreading requirement.

-- 
Jouni Malinen                                            PGP id EFC895FA