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

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Message-ID: <CAJZ5v0iqy0yMJP5H7ub67R8R6i42=TcS_6+VF-+fWrM-9tYFQA@mail.gmail.com>
Date:   Fri, 23 Jun 2023 16:52:55 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Evan Quan <evan.quan@....com>
Cc:     rafael@...nel.org, lenb@...nel.org, alexander.deucher@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...il.com,
        daniel@...ll.ch, johannes@...solutions.net, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        mario.limonciello@....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, Jun 21, 2023 at 7:47 AM Evan Quan <evan.quan@....com> wrote:
>
> From: Mario Limonciello <mario.limonciello@....com>
>
> Due to electrical and mechanical constraints in certain platform designs
> there may be likely interference of relatively high-powered harmonics of
> the (G-)DDR memory clocks with local radio module frequency bands used
> by Wifi 6/6e/7.
>
> To mitigate this, AMD has introduced an ACPI based mechanism that
> devices can use to notify active use of particular frequencies so
> that devices can make relative internal adjustments as necessary
> to avoid this resonance.
>
> In order for a device to support this, the expected flow for device
> driver or subsystems:
>
> Drivers/subsystems contributing frequencies:
>
> 1) During probe, check `wbrf_supported_producer` to see if WBRF supported

The prefix should be acpi_wbrf_ or acpi_amd_wbrf_ even, so it is clear
that this uses ACPI and is AMD-specific.

Whether or not there needs to be an intermediate library wrapped
around this is a different matter.