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

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Message-ID: <CAMuHMdUrpnsvc_G33FQA6GtqNowidMrjjYBEZW-_biBMYvqjgQ@mail.gmail.com>
Date:   Wed, 13 Jul 2022 13:39:05 +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, Jul 13, 2022 at 3:40 AM Saravana Kannan <saravanak@...gle.com> wrote:
> On Tue, Jul 5, 2022 at 2:11 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > 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:
>
> 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.

Comparison of dmesg before/after enabling debugging, for
related nodes:

    +interrupt-controller@...c0000 Linked as a fwnode consumer to
clock-controller@...50000

    +pmic@58 Linked as a fwnode consumer to interrupt-controller@...c0000
    +regulator@68 Linked as a fwnode consumer to interrupt-controller@...c0000

Other user of irqc

    +ethernet@...00000 Linked as a fwnode consumer to clock-controller@...50000
    +ethernet@...00000 Linked as a fwnode consumer to pinctrl@...60000
    +ethernet-phy@1 Linked as a fwnode consumer to interrupt-controller@...c0000
    +ethernet-phy@1 Linked as a fwnode consumer to gpio@...55000

PHY linked correctly to consumers

    +device: 'e61c0000.interrupt-controller': device_add
    +device: 'platform:e6150000.clock-controller--platform:e61c0000.interrupt-controller':
device_add
    +devices_kset: Moving e61c0000.interrupt-controller to end of list
    +platform e61c0000.interrupt-controller: Linked as a consumer to
e6150000.clock-controller
    +interrupt-controller@...c0000 Dropping the fwnode link to
clock-controller@...50000
    +platform e61c0000.interrupt-controller: error -EPROBE_DEFER:
supplier e6150000.clock-controller not ready

Tried to probe irqc (why? consumer not ready), deferred.

    +device: 'platform:e61c0000.interrupt-controller--platform:e60b0000.i2c':
device_add
    +platform e60b0000.i2c: Linked as a sync state only consumer to
e61c0000.interrupt-controller

I guess sync state means through other (child) consumers (pmic,
regulator) above?

    +device: 'ee700000.ethernet': device_add
    +device: 'platform:e6060000.pinctrl--platform:ee700000.ethernet': device_add
    +devices_kset: Moving ee700000.ethernet to end of list
    +platform ee700000.ethernet: Linked as a consumer to e6060000.pinctrl
    +ethernet@...00000 Dropping the fwnode link to pinctrl@...60000
    +device: 'platform:e6150000.clock-controller--platform:ee700000.ethernet':
device_add
    +devices_kset: Moving ee700000.ethernet to end of list
    +platform ee700000.ethernet: Linked as a consumer to
e6150000.clock-controller
    +ethernet@...00000 Dropping the fwnode link to clock-controller@...50000
    +device: 'platform:e6055000.gpio--platform:ee700000.ethernet': device_add
    +platform ee700000.ethernet: Linked as a sync state only consumer
to e6055000.gpio
    +device: 'platform:e61c0000.interrupt-controller--platform:ee700000.ethernet':
device_add
    +platform ee700000.ethernet: Linked as a sync state only consumer
to e61c0000.interrupt-controller

Hence linking ethernet to child (phy) consumers.

    +device: 'ee700000.ethernet-ffffffff': device_add

Probing ethernet...

     libphy: fwnode_get_phy_id: fwnode
/soc/ethernet@...00000/ethernet-phy@1 phy_id = 0x00221537
     libphy: fwnode_get_phy_id: fwnode
/soc/ethernet@...00000/ethernet-phy@1 phy_id = 0x00221537
    +fwnode_mdiobus_phy_device_register: fwnode_irq_get() returned -517
    +fwnode_mdiobus_phy_device_register: ignoring -EPROBE_DEFER

This is the part that got changed by this patch.

    +device: 'ee700000.ethernet-ffffffff:01': device_add
    +device: 'platform:e6055000.gpio--mdio_bus:ee700000.ethernet-ffffffff:01':
device_add
    +devices_kset: Moving ee700000.ethernet-ffffffff:01 to end of list
    +mdio_bus ee700000.ethernet-ffffffff:01: Linked as a consumer to
e6055000.gpio
    +ethernet-phy@1 Dropping the fwnode link to gpio@...55000
    +device: 'platform:e61c0000.interrupt-controller--mdio_bus:ee700000.ethernet-ffffffff:01':
device_add
    +devices_kset: Moving ee700000.ethernet-ffffffff:01 to end of list
    +mdio_bus ee700000.ethernet-ffffffff:01: Linked as a consumer to
e61c0000.interrupt-controller
    +ethernet-phy@1 Dropping the fwnode link to interrupt-controller@...c0000
    +mdio_bus ee700000.ethernet-ffffffff:01: error -EPROBE_DEFER:
supplier e61c0000.interrupt-controller not ready

Why was ethernet probed this early?
We knew the supplier of the phy was still missing?

    +device: 'eth1': device_add
     sh-eth ee700000.ethernet eth1: Base address at 0xee700000,
2e:09:0a:00:6d:85, IRQ 104.
    +sh-eth ee700000.ethernet: Dropping the link to e6055000.gpio
    +device: 'platform:e6055000.gpio--platform:ee700000.ethernet':
device_unregister
    +sh-eth ee700000.ethernet: Dropping the link to
e61c0000.interrupt-controller
    +device: 'platform:e61c0000.interrupt-controller--platform:ee700000.ethernet':
device_unregister

    +devices_kset: Moving e61c0000.interrupt-controller to end of list
    +devices_kset: Moving ee700000.ethernet-ffffffff:01 to end of list
     renesas_irqc e61c0000.interrupt-controller: driving 10 irqs

Finally, irqc is probed.

    +device: '6-0058': device_add
    +device: 'platform:e61c0000.interrupt-controller--i2c:6-0058': device_add
    +devices_kset: Moving 6-0058 to end of list
    +i2c 6-0058: Linked as a consumer to e61c0000.interrupt-controller
    +pmic@58 Dropping the fwnode link to interrupt-controller@...c0000

    +device: '6-0068': device_add
    +device: 'platform:e61c0000.interrupt-controller--i2c:6-0068': device_add
    +devices_kset: Moving 6-0068 to end of list
    +i2c 6-0068: Linked as a consumer to e61c0000.interrupt-controller
    +regulator@68 Dropping the fwnode link to interrupt-controller@...c0000

Propagating other irqc suppliers to the parent of their consumers

    +i2c-sh_mobile e60b0000.i2c: Dropping the link to
e61c0000.interrupt-controller
    +device: 'platform:e61c0000.interrupt-controller--platform:e60b0000.i2c':
device_unregister

    +devices_kset: Moving ee700000.ethernet-ffffffff:01 to end of list

     Micrel KSZ8041RNLI ee700000.ethernet-ffffffff:01: attached PHY
driver (mii_bus:phy_addr=ee700000.ethernet-ffffffff:01, irq=POLL)
     sh-eth ee700000.ethernet eth1: Link is Up - 100Mbps/Full - flow control off
     Sending DHCP requests ., OK

> >     -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?

That didn't help much, as this is the messenger, not the cause.

Thanks!

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