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

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Message-ID: <CAGETcx-jU5+Tc0Qkt1e4QY0YprYSp-4A+MoaSRjpdPp_8tZm5g@mail.gmail.com>
Date:   Tue, 12 Jul 2022 18:40:08 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
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()

On Tue, Jul 5, 2022 at 2:11 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> 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.

No worries. Appreciate any testing help.

>
> 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:

I'd still expect the device link to have been created properly for
this phy device. Could you enable the logging in device_link_add() to
check the link is created between the phy and the IRQ?

My guess is that this probably has something to do with phys being
attached to drivers differently.

>
>     -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)

Can you drop a WARN() where this is printed to get the stack trace to
check my hypothesis?

-Saravana

>
> 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