linux-kernel - Re: [PATCH V4 1/8] drivers/acpi: Add support for Wifi band RF mitigations

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Message-ID: <3e337dc0482e16e2aaa4090b613dc8dea7803fa8.camel@sipsolutions.net>
Date:   Thu, 22 Jun 2023 00:18:53 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Andrew Lunn <andrew@...n.ch>,
        "Limonciello, Mario" <mario.limonciello@....com>
Cc:     Evan Quan <evan.quan@....com>, rafael@...nel.org, lenb@...nel.org,
        alexander.deucher@....com, christian.koenig@....com,
        Xinhui.Pan@....com, airlied@...il.com, daniel@...ll.ch,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, mdaenzer@...hat.com,
        maarten.lankhorst@...ux.intel.com, tzimmermann@...e.de,
        hdegoede@...hat.com, jingyuwang_vip@....com, lijo.lazar@....com,
        jim.cromie@...il.com, bellosilicio@...il.com,
        andrealmeid@...lia.com, trix@...hat.com, jsg@....id.au,
        arnd@...db.de, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH V4 1/8] drivers/acpi: Add support for Wifi band RF
 mitigations

On Wed, 2023-06-21 at 21:25 +0200, Andrew Lunn wrote:
> > ACPI core does has notifiers that are used, but they don't work the same.
> > If you look at patch 4, you'll see amdgpu registers and unregisters using
> > both
> > 
> > acpi_install_notify_handler()
> > and
> > acpi_remove_notify_handler()
> > 
> > If we supported both ACPI notifications and non-ACPI notifications
> > all consumers would have to have support to register and use both types.
> 
> Why would you want to support ACPI notifications and non-ACPI
> notifications? All you need is wbrf notification.
> 
> The new wbrf.c should implement wbrf_install_notify_handler() and
> wbrf_remove_notify_handler().
> 
> As to where to put wbrf.c? I guess either drivers/base/ or
> drivers/wbrf/. Maybe ask GregKH?

Not sure it should even be called WBRF at that point, but hey :)

Honestly I'm not sure though we need this complexity right now? I mean,
it'd be really easy to replace the calls in mac80211 with some other
more generalised calls in the future?

You need some really deep platform/hardware level knowledge and
involvement to do this, so I don't think it's something that someone
will come up with very easily for a DT-based platform...

If we do something with a notifier chain in the future, we can just
install one in the ACPI code too, and react indirectly rather than
calling from wifi to the ACPI directly.

johannes