linux-kernel - Re: [PATCH] iio: dac: ad5593r: Dynamically set AD5593R channel modes

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Date:   Mon, 31 Aug 2020 15:45:42 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     AceLan Kao <acelan.kao@...onical.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     William Sung <william.sung@...antech.com.tw>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Campion Kang <Campion.Kang@...antech.com.tw>
Subject: Re: [PATCH] iio: dac: ad5593r: Dynamically set AD5593R channel modes

On Mon, Aug 31, 2020 at 2:28 PM AceLan Kao <acelan.kao@...onical.com> wrote:
> This patch is mainly for Advantech's UNO-420[1] which is a x86-based platform.
> This platform is more like a development platform for customers to
> customize their products,
> so, specify the channel modes in ACPI table is not generic enough,
> that's why William submit this patch.
>
> Are there other ways to specify or pass values to the module without
> using module parameters?
> It's good if we can leverage sysfs, but I don't know if there is one
> for this scenario.

Can we provide DT bindings for that and use then in ACPI? ACPI has a
possibility to reuse DT properties and compatible strings [1]. As far
as I can see the driver uses fwnode API, so it supports ACPI case
already [2]. So, what prevents you to utilize 'adi,mode' property?

Also, we accept examples of ASL excerpt in meta-acpi project [3]. It
has already plenty of examples [4] how to use PRP0001 for DIY /
development boards.

So, take all together I think this patch is simple redundant.

[1]: https://www.kernel.org/doc/html/latest/firmware-guide/acpi/enumeration.html#device-tree-namespace-link-device-id
[2]: https://elixir.bootlin.com/linux/v5.9-rc3/source/Documentation/devicetree/bindings/iio/dac/ad5592r.txt
[3]: https://github.com/westeri/meta-acpi
[4]: https://github.com/westeri/meta-acpi/tree/master/recipes-bsp/acpi-tables/samples

P.S. Jonathan, it seems this driver has artificial ACPI HID. We
probably have to remove it. However, ADS is indeed reserved for Analog
Devices in PNP registry. Can we have AD's official answer on this?
Cc'ing additional AD people.

> 1. https://www.advantech.com/products/9a0cc561-8fc2-4e22-969c-9df90a3952b5/uno-420/mod_2d6a546b-39e3-4bc4-bbf4-ac89e6b7667c


-- 
With Best Regards,
Andy Shevchenko