linux-kernel - Re: [PATCH v2 3/9] net: mdio: Delete usage of driver_deferred_probe_check

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Date:   Tue, 5 Jul 2022 11:11:21 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Linux IOMMU <iommu@...ts.linux-foundation.org>,
        netdev <netdev@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v2 3/9] net: mdio: Delete usage of driver_deferred_probe_check_state()

Hi Saravana,

On Wed, Jun 1, 2022 at 2:44 PM Saravana Kannan <saravanak@...gle.com> wrote:
> Now that fw_devlink=on by default and fw_devlink supports interrupt
> properties, the execution will never get to the point where
> driver_deferred_probe_check_state() is called before the supplier has
> probed successfully or before deferred probe timeout has expired.
>
> So, delete the call and replace it with -ENODEV.
>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>

Thanks for your patch, which is now commit f8217275b57aa48d ("net:
mdio: Delete usage of driver_deferred_probe_check_state()") in
driver-core/driver-core-next.

Seems like I missed something when providing my T-b for this series,
sorry for that.

arch/arm/boot/dts/r8a7791-koelsch.dts has:

    &ether {
            pinctrl-0 = <&ether_pins>, <&phy1_pins>;
            pinctrl-names = "default";

            phy-handle = <&phy1>;
            renesas,ether-link-active-low;
            status = "okay";

            phy1: ethernet-phy@1 {
                    compatible = "ethernet-phy-id0022.1537",
                                 "ethernet-phy-ieee802.3-c22";
                    reg = <1>;
                    interrupt-parent = <&irqc0>;
                    interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
                    micrel,led-mode = <1>;
                    reset-gpios = <&gpio5 22 GPIO_ACTIVE_LOW>;
            };
    };

Despite the interrupts property, &ether is now probed before irqc0
(interrupt-controller@...c0000 in arch/arm/boot/dts/r8a7791.dtsi),
causing the PHY not finding its interrupt, and resorting to polling:

    -Micrel KSZ8041RNLI ee700000.ethernet-ffffffff:01: attached PHY
driver (mii_bus:phy_addr=ee700000.ethernet-ffffffff:01, irq=185)
    +Micrel KSZ8041RNLI ee700000.ethernet-ffffffff:01: attached PHY
driver (mii_bus:phy_addr=ee700000.ethernet-ffffffff:01, irq=POLL)

Reverting this commit, and commit 9cbffc7a59561be9 ("driver core:
Delete driver_deferred_probe_check_state()") fixes that.

> --- a/drivers/net/mdio/fwnode_mdio.c
> +++ b/drivers/net/mdio/fwnode_mdio.c
> @@ -47,9 +47,7 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
>          * just fall back to poll mode
>          */
>         if (rc == -EPROBE_DEFER)
> -               rc = driver_deferred_probe_check_state(&phy->mdio.dev);
> -       if (rc == -EPROBE_DEFER)
> -               return rc;
> +               rc = -ENODEV;
>
>         if (rc > 0) {
>                 phy->irq = rc;

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds