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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 30 Sep 2020 18:37:09 +0200
Message-ID: <CAJZ5v0jP8L=bBMYTUkYCSwN=fy8dwTdjqu1JurSxTa2bAHRLew@mail.gmail.com>
Subject: Re: [net-next PATCH v1 1/7] Documentation: ACPI: DSD: Document MDIO PHY
To:     Calvin Johnson <calvin.johnson@oss.nxp.com>
Cc:     Grant Likely <grant.likely@arm.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Jeremy Linton <jeremy.linton@arm.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Cristi Sovaiala <cristian.sovaiala@nxp.com>,
        Florin Laurentiu Chiculita <florinlaurentiu.chiculita@nxp.com>,
        Ioana Ciornei <ioana.ciornei@nxp.com>,
        Madalin Bucur <madalin.bucur@oss.nxp.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux.cj@gmail.com, netdev <netdev@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Diana Madalina Craciun <diana.craciun@nxp.com>,
        Laurentiu Tudor <laurentiu.tudor@nxp.com>,
        Len Brown <lenb@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
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On Wed, Sep 30, 2020 at 6:05 PM Calvin Johnson
<calvin.johnson@oss.nxp.com> wrote:
>
> Introduce ACPI mechanism to get PHYs registered on a MDIO bus and
> provide them to be connected to MAC.
>
> Describe properties "phy-handle" and "phy-mode".
>
> Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> ---
>
>  Documentation/firmware-guide/acpi/dsd/phy.rst | 78 +++++++++++++++++++
>  1 file changed, 78 insertions(+)
>  create mode 100644 Documentation/firmware-guide/acpi/dsd/phy.rst
>
> diff --git a/Documentation/firmware-guide/acpi/dsd/phy.rst b/Documentation/firmware-guide/acpi/dsd/phy.rst
> new file mode 100644
> index 000000000000..f10feb24ec1c
> --- /dev/null
> +++ b/Documentation/firmware-guide/acpi/dsd/phy.rst
> @@ -0,0 +1,78 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=========================
> +MDIO bus and PHYs in ACPI
> +=========================
> +
> +The PHYs on an mdiobus are probed and registered using
> +fwnode_mdiobus_register_phy().
> +Later, for connecting these PHYs to MAC, the PHYs registered on the
> +mdiobus have to be referenced.
> +
> +phy-handle
> +-----------
> +For each MAC node, a property "phy-handle" is used to reference the
> +PHY that is registered on an MDIO bus.

It is not clear what "a property" means in this context.

This should refer to the documents introducing the _DSD-based generic
device properties rules, including the GUID used below.

You need to say whether or not the property is mandatory and if it
isn't mandatory, you need to say what the lack of it means.

> +
> +phy-mode
> +--------
> +Property "phy-mode" defines the type of PHY interface.

This needs to be more detailed too, IMO.  At the very least, please
list all of the possible values of it and document their meaning.

> +
> +An example of this is shown below::
> +
> +DSDT entry for MACs where PHY nodes are referenced
> +--------------------------------------------------
> +       Scope(\_SB.MCE0.PR17) // 1G
> +       {
> +         Name (_DSD, Package () {
> +            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> +                Package () {
> +                    Package (2) {"phy-mode", "rgmii-id"},
> +                    Package (2) {"phy-handle", Package (){\_SB.MDI0.PHY1}}

What is "phy-handle"?

You haven't introduced it above.

> +             }
> +          })
> +       }
> +
> +       Scope(\_SB.MCE0.PR18) // 1G
> +       {
> +         Name (_DSD, Package () {
> +           ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> +               Package () {
> +                   Package (2) {"phy-mode", "rgmii-id"},
> +                   Package (2) {"phy-handle", Package (){\_SB.MDI0.PHY2}}
> +           }
> +         })
> +       }
> +
> +DSDT entry for MDIO node
> +------------------------
> +a) Silicon Component

What is this device, exactly?

> +--------------------
> +       Scope(_SB)
> +       {
> +         Device(MDI0) {
> +           Name(_HID, "NXP0006")
> +           Name(_CCA, 1)
> +           Name(_UID, 0)
> +           Name(_CRS, ResourceTemplate() {
> +             Memory32Fixed(ReadWrite, MDI0_BASE, MDI_LEN)
> +             Interrupt(ResourceConsumer, Level, ActiveHigh, Shared)
> +              {
> +                MDI0_IT
> +              }
> +           }) // end of _CRS for MDI0
> +         } // end of MDI0
> +       }
> +
> +b) Platform Component
> +---------------------
> +       Scope(\_SB.MDI0)
> +       {
> +         Device(PHY1) {
> +           Name (_ADR, 0x1)
> +         } // end of PHY1
> +
> +         Device(PHY2) {
> +           Name (_ADR, 0x2)
> +         } // end of PHY2
> +       }
> --

What is the connection between the last two pieces of ASL and the _DSD
definitions above?