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Date:   Mon, 20 Jun 2022 21:07:32 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Marcin Wojtas <mw@semihalf.com>, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, netdev@vger.kernel.org,
        rafael@kernel.org, lenb@kernel.org, vivien.didelot@gmail.com,
        f.fainelli@gmail.com, olteanv@gmail.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        linux@armlinux.org.uk, hkallweit1@gmail.com, gjb@semihalf.com,
        jaz@semihalf.com, tn@semihalf.com, Samer.El-Haj-Mahmoud@arm.com,
        upstream@semihalf.com
Subject: Re: [net-next: PATCH 00/12] ACPI support for DSA
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 <YrC0oKdDSjQTgUtM@lunn.ch>
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On Mon, Jun 20, 2022 at 07:55:44PM +0200, Andrew Lunn wrote:
> On Mon, Jun 20, 2022 at 05:02:13PM +0200, Marcin Wojtas wrote:

...

> > It turned out that without much hassle it is possible to describe
> > DSA-compliant switches as child devices of the MDIO busses, which are
> > responsible for their enumeration based on the standard _ADR fields and
> > description in _DSD objects under 'device properties' UUID [1].
> 
> No surprises there. That is how the DT binding works. And the current
> ACPI concept is basically DT in different words. Maybe the more
> important question is, is rewording DT in ACPI the correct approach,
> or should you bo doing a more native ACPI implementation? I cannot
> answer that, you need to ask the ACPI maintainers.

You beat me up to this. I also was about to mention that the problem with such
conversions (like this series does) is not in the code. It's simplest part. The
problem is bindings and how you get them to be a standard (at least de facto).

> > Note that for now cascade topology remains unsupported in ACPI world
> > (based on "dsa" label and "link" property values). It seems to be feasible,
> > but would extend this patchset due to necessity of of_phandle_iterator
> > migration to fwnode_. Leave it as a possible future step.
> 
> We really do need to ensure this is possible. You are setting an ABI
> here, which everybody else in the ACPI world needs to follow. Cascaded
> switches is fundamental to DSA, it is the D in DSA. So i would prefer
> that you at least define and document the binding for D in DSA and get
> it sanity checked by the ACPI people.

-- 
With Best Regards,
Andy Shevchenko