Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220620150225.1307946-1-mw@semihalf.com> <20220620150225.1307946-10-mw@semihalf.com>
 <YrC6Ihd4I13ctL18@lunn.ch>
In-Reply-To: <YrC6Ihd4I13ctL18@lunn.ch>
From:   Marcin Wojtas <mw@semihalf.com>
Date:   Tue, 21 Jun 2022 01:21:42 +0200
Message-ID: <CAPv3WKeLYDR3PuspOGU-oVf8tak5aNRDNP0nEN-jDJmoWa-USg@mail.gmail.com>
Subject: Re: [net-next: PATCH 09/12] Documentation: ACPI: DSD: introduce DSA description
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Len Brown <lenb@kernel.org>, vivien.didelot@gmail.com,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>, pabeni@redhat.com,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Grzegorz Bernacki <gjb@semihalf.com>,
        Grzegorz Jaszczyk <jaz@semihalf.com>,
        Tomasz Nowicki <tn@semihalf.com>,
        Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>,
        upstream@semihalf.com
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

pon., 20 cze 2022 o 20:19 Andrew Lunn <andrew@lunn.ch> napisa=C5=82(a):
>
> On Mon, Jun 20, 2022 at 05:02:22PM +0200, Marcin Wojtas wrote:
> > Describe the Distributed Switch Architecture (DSA) - compliant
> > MDIO devices. In ACPI world they are represented as children
> > 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].
>
> I would say this is too limiting. In the DT world, they are not
> limited to MDIO children. They can be I2C children, SPI children
> etc. There are plenty of I2C switches and SPI switches. This is
> actually something we got wrong with the first DT binding. We simply
> translated the platform data in DT, and at that time, there was only
> MDIO switches supported. That was a real blocker to I2C, SPI and MMIO
> devices until we discarded the DT binding and had a second go.
>
> DSA switches are just devices on a bus, any sort of bus.
>
> Look at Documentation/devicetree/binding/net/dsa/dsa.yaml. There is no
> reference to MDIO.
>
> I would expect the same with ACPI. Somehow the bus enumerates and
> instantiates a device on the bus. The device then registers itself
> with the DSA core. The DSA core does not care what sort of bus it is
> on, that is the drivers problem.
>

Thanks for mentioning the other options. It makes things easier and
the MDIO as current strict dependency will be dropped.

Best regards,
Marcin