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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Sun, 2 Jan 2022 06:58:42 +0100
Message-ID: <CACRpkdbWs=5s-5qZXoDOf+f-y=c6XZOGZb7w0LL7bDEJpnnVpw@mail.gmail.com>
Subject: Re: [PATCH 16/34] brcmfmac: acpi: Add support for fetching Apple ACPI properties
To:     Hector Martin <marcan@marcan.st>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Arend van Spriel <aspriel@gmail.com>,
        Franky Lin <franky.lin@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Chi-hsien Lin <chi-hsien.lin@infineon.com>,
        Wright Feng <wright.feng@infineon.com>,
        Chung-hsien Hsu <chung-hsien.hsu@infineon.com>,
        Sven Peter <sven@svenpeter.dev>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        Mark Kettenis <kettenis@openbsd.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>,
        Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>,
        Hans de Goede <hdegoede@redhat.com>,
        "John W. Linville" <linville@tuxdriver.com>,
        "Daniel (Deognyoun) Kim" <dekim@broadcom.com>,
        "brian m. carlson" <sandals@crustytoothpaste.net>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, brcm80211-dev-list.pdl@broadcom.com,
        SHA-cyfmac-dev-list@infineon.com
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On Sun, Dec 26, 2021 at 4:38 PM Hector Martin <marcan@marcan.st> wrote:

> On DT platforms, the module-instance and antenna-sku-info properties
> are passed in the DT. On ACPI platforms, module-instance is passed via
> the analogous Apple device property mechanism, while the antenna SKU
> info is instead obtained via an ACPI method that grabs it from
> non-volatile storage.
>
> Add support for this, to allow proper firmware selection on Apple
> platforms.
>
> Signed-off-by: Hector Martin <marcan@marcan.st>

If the strings treated here are exactly the same as for the device tree,
you should be able to just use "devprops" (firmware node) to handle it
abstractly, and then the respective DT and ACPI backend will provide
the properties.

I don't know if this patch I made recently is enough of an examples:
https://lore.kernel.org/linux-hwmon/20211206020423.62402-2-linus.walleij@linaro.org/

If the ACPI and DT differs a lot in format and strings etc it may not
be worth it.

Yours,
Linus Walleij