linux-kernel - Re: [net-next: PATCH v2 5/5] net: mvpp2: enable ACPI support in the driver

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Message-ID: <CAPv3WKfB6_5hPw2M_GOMHVc_soPyzgMqQJ=tG5qOfSe_397z9A@mail.gmail.com>
Date:   Tue, 2 Jan 2018 14:55:39 +0100
From:   Marcin Wojtas <mw@...ihalf.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        netdev <netdev@...r.kernel.org>, linux-acpi@...r.kernel.org,
        Graeme Gregory <graeme.gregory@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Antoine Ténart <antoine.tenart@...e-electrons.com>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Gregory Clément 
        <gregory.clement@...e-electrons.com>,
        Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
        nadavh@...vell.com, Neta Zur Hershkovits <neta@...vell.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>,
        Tomasz Nowicki <tn@...ihalf.com>
Subject: Re: [net-next: PATCH v2 5/5] net: mvpp2: enable ACPI support in the driver

Hi Andrew,

2018-01-02 14:33 GMT+01:00 Andrew Lunn <andrew@...n.ch>:
>> Apart from the phylink's SFP support that may require in-band
>> management, it's an alternative to the normal PHY handling. Once MDIO
>> bus + PHYs are supported for ACPI, phylib support will be used instead
>> of the IRQs, so there should be no problem here.
>
> Hi Marcin
>
> However, phylib and phylink can use IRQs. The PHY can interrupt when
> there is a change of state. This can be seen in the DT binding
> documentation example:
>
> ethernet-phy@0 {
>         compatible = "ethernet-phy-id0141.0e90", "ethernet-phy-ieee802.3-c22";
>         interrupt-parent = <&PIC>;
>         interrupts = <35 IRQ_TYPE_EDGE_RISING>;
>         reg = <0>;
>
> Whatever ACPI support you propose needs to include interrupts.
>
> May i suggest you take a look at
> arch/arm/boot/dts/vf610-zii-dev-rev-c.dts and ensure your ACPI work
> can support this. I know you tend to concentrate of Marvell parts.
> Although it is a Freescale SoC, the Ethernet parts are all Marvell.
>
> The SoC exports an MDIO bus. We then have an MDIO multiplexer, which
> exports 8 MDIO busses. Of these only 2 are used in this design. Each
> bus has an Ethernet switch. Each switch has an MDIO bus, which the
> embedded PHYs are on. The Ethernet switch is also an interrupt
> controller for the PHYs interrupts. So the PHYs have interrupt
> properties pointing back to the switch.
>

I thought you were pointing possible problems in mvpp2 with PHY/link
interrupts, sorry. Now I get it :)

Indeed in of_mdio_bus_register_phy, there is of_irq_get. This is more
a discussion for a MDIO bus / ACPI patchset, but we either find a way
to use IRQs with ACPI obtained from child nodes or for this world the
functionality will be limited (at least for the beginning).

Best regards,
Marcin