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Date:   Thu, 3 Mar 2022 23:56:47 +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 9/9] DFS: introduce radar_background parameter to config
 file
Message-ID: <20220303215647.GA33342@w1.fi>
References: <cover.1640014128.git.lorenzo@kernel.org>
 <3683c678668c4de0ee849974977cf56e64c7162c.1640014128.git.lorenzo@kernel.org>
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On Mon, Dec 20, 2021 at 04:48:24PM +0100, Lorenzo Bianconi wrote:
> Introduce radar_background parameter to configuration file
> in order to enable/disable background radar/CAC detection.

What's the use case for this new parameter and the configuration having
to explicitly enable this functionality? Is there a reason for not doing
this in cases where the driver supports this capability? It looks like
patches 1..8 were enabling this functionality automatically and it is
only this final patch that makes it depend on a configuration parameter
(which is default by default).

> diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
> @@ -143,6 +143,13 @@ ssid=test
> +# Enable radar/CAC detection through a dedicated background chain available on
> +# some hw. The chain can't be used to transmits or receives frames.
> +# This feature allows to avoid CAC downtime switching on a different channel
> +# during CAC detection on the selected radar channel.
> +# (default: 0 = disabled, 1 = enabled)
> +#radar_background=0

How would someone writing hostapd configuration know when to enable
this? Or maybe more importantly, when one should not enable this? Would
use of that dedicated background chain result in some other capabilities
getting reduced?

This is also a bit unclear on what happens if the driver does not
support this capability and radar_background=1 is explicitly set in the
configuration.

-- 
Jouni Malinen                                            PGP id EFC895FA