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Date:   Wed, 22 Jun 2022 13:22:15 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Marcin Wojtas <mw@semihalf.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Subject: Re: [net-next: PATCH 09/12] Documentation: ACPI: DSD: introduce DSA
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> > It's not device on MDIO bus, but the MDIO controller's register itself
> > (this _CSR belongs to the parent, subnodes do not refer to it in any
> > way). The child device requires only _ADR (or whatever else is needed
> > for the case the DSA device is attached to SPI/I2C controllers).
> 
> More and more the idea of standardizing the MDIOSerialBus() resource looks
> plausible. The _ADR() usage is a bit grey area in ACPI specification. Maybe
> someone can also make it descriptive, so Microsoft and others won't utilize
> _ADR() in any level of weirdness.

I don't know if it makes any difference, but there are two protocols
spoken over MDIO, c22 and c45, specified in clause 22 and clause 45 of
the 802.3 specification. In some conditions, you need to specify which
protocol to speak to a device at a particular address. In DT we
indicate this with the compatible string, when maybe it should really
be considered as an extension of the address.

If somebody does produce a draft for MDIOSerialBus() i'm happy to
review it.

       Andrew