Re: [PATCH v2 3/9] net: mdio: Delete usage of driver_deferred_probe_check_state()

Geert Uytterhoeven
2022-07-13T11:45:50Z

Hi Saravana,

On Wed, Jul 13, 2022 at 3:40 AM Saravana Kannan <saravanak@google.com> wrote:
> On Tue, Jul 5, 2022 at 2:11 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Wed, Jun 1, 2022 at 2:44 PM Saravana Kannan <saravanak@google.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@google.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@e61c0000 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@e61c0000 Linked as a fwnode consumer to
clock-controller@e6150000

+pmic@58 Linked as a fwnode consumer to interrupt-controller@e61c0000
+regulator@68 Linked as a fwnode consumer to interrupt-controller@e61c0000

Other user of irqc

+ethernet@ee700000 Linked as a fwnode consumer to clock-controller@e6150000
+ethernet@ee700000 Linked as a fwnode consumer to pinctrl@e6060000
+ethernet-phy@1 Linked as a fwnode consumer to interrupt-controller@e61c0000
+ethernet-phy@1 Linked as a fwnode consumer to gpio@e6055000

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@e61c0000 Dropping the fwnode link to
clock-controller@e6150000
+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@ee700000 Dropping the fwnode link to pinctrl@e6060000
+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@ee700000 Dropping the fwnode link to clock-controller@e6150000
+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@ee700000/ethernet-phy@1 phy_id = 0x00221537
libphy: fwnode_get_phy_id: fwnode
/soc/ethernet@ee700000/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@e6055000
+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@e61c0000
+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@e61c0000

+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@e61c0000

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@linux-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