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From: Saravana Kannan <saravanak@google.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Len Brown <lenb@kernel.org>,
	Alvin Sipraga <ALSI@bang-olufsen.dk>,
	kernel-team@android.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [PATCH v1 1/2] driver core: fw_devlink: Add support for FWNODE_FLAG_BROKEN_PARENT
Date: Thu, 26 Aug 2021 16:44:58 -0700	[thread overview]
Message-ID: <CAGETcx_h6moWbS7m4hPm6Ub3T0tWayUQkppjevkYyiA=8AmACw@mail.gmail.com> (raw)
In-Reply-To: <YSf/Mps9E77/6kZX@lunn.ch>

On Thu, Aug 26, 2021 at 1:53 PM Andrew Lunn <andrew@lunn.ch> wrote:
>
> > The  DT node in [2] is probed by realtek_smi_probe() [3]. The call flow is:
> > realtek_smi_probe()
> >   -> dsa_register_switch()
> >     -> dsa_switch_probe()
> >       -> dsa_tree_setup()
> >         -> dsa_tree_setup_switches()
> >           -> dsa_switch_setup()
> >             -> ds->ops->setup(ds)
> >               -> rtl8366rb_setup()
> >                 -> realtek_smi_setup_mdio()
> >                   -> of_mdiobus_register()
> >                      This scans the MDIO bus/DT and device_add()s the PHYs
> >           -> dsa_port_setup()
> >             -> dsa_port_link_register_of()
> >               -> dsa_port_phylink_register()
> >                 -> phylink_of_phy_connect()
> >                   -> phylink_fwnode_phy_connect()
> >                     -> phy_attach_direct()
> >                        This checks if PHY device has already probed (by
> >                        checking for dev->driver). If not, it forces the
> >                        probe of the PHY using one of the generic PHY
> >                        drivers.
> >
> > So within dsa_register_switch() the PHY device is added and then
> > expected to have probed in the same thread/calling context. As stated
> > earlier, this is not guaranteed by the driver core.
>
> Have you looked at:
>
> commit 16983507742cbcaa5592af530872a82e82fb9c51
> Author: Heiner Kallweit <hkallweit1@gmail.com>
> Date:   Fri Mar 27 01:00:22 2020 +0100
>
>     net: phy: probe PHY drivers synchronously
>
> See the full commit message, but the code change is:
>
> iff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 3b8f6b0b47b5..d543df282365 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -2577,6 +2577,7 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner)
>         new_driver->mdiodrv.driver.probe = phy_probe;
>         new_driver->mdiodrv.driver.remove = phy_remove;
>         new_driver->mdiodrv.driver.owner = owner;
> +       new_driver->mdiodrv.driver.probe_type = PROBE_FORCE_SYNCHRONOUS;
>
>         retval = driver_register(&new_driver->mdiodrv.driver);
>         if (retval) {
>
> How does this add to the overall picture?

Doesn't add much to the discussion. In the example I gave, the driver
already does synchronous probing. If the device can't probe
successfully because a supplier isn't ready, it doesn't matter if it's
a synchronous probe. The probe would still be deferred and we'll hit
the same issue. Even in the situation the commit [5] describes, if
parallelized probing is done and the PHY depended on something (say a
clock), you'd still end up not probing the PHY even if the driver is
present and the generic PHY would end up force probing it.

[5] - https://lore.kernel.org/netdev/612b81d5-c4c1-5e20-a667-893eeeef0bf5@gmail.com/

-Saravana

  reply	other threads:[~2021-08-26 23:45 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26  7:45 [PATCH v1 0/2] Fix rtl8366rb issues with fw_devlink=on Saravana Kannan
2021-08-26  7:45 ` [PATCH v1 1/2] driver core: fw_devlink: Add support for FWNODE_FLAG_BROKEN_PARENT Saravana Kannan
2021-08-26 13:13   ` Andrew Lunn
2021-08-26 19:56     ` Saravana Kannan
2021-08-26 20:53       ` Andrew Lunn
2021-08-26 23:44         ` Saravana Kannan [this message]
2021-08-27  1:23           ` Andrew Lunn
2021-08-27  4:02             ` Saravana Kannan
2021-08-27 13:44               ` Andrew Lunn
2021-08-27 18:06                 ` Saravana Kannan
2021-08-27 20:11                   ` Andrew Lunn
2021-08-27 21:33                     ` Saravana Kannan
2021-08-28 17:01                       ` Andrew Lunn
2021-08-30 19:03                         ` Saravana Kannan
2021-08-31 13:16                           ` Andrew Lunn
2021-08-31 19:26                             ` Saravana Kannan
2021-08-31 22:05                               ` Andrew Lunn
2021-08-31 22:18                                 ` Saravana Kannan
2021-08-31 23:02                                   ` Andrew Lunn
2021-08-31 23:18                                     ` Vladimir Oltean
2021-08-31 23:27                                       ` Andrew Lunn
2021-09-01  1:28                                       ` Vladimir Oltean
2021-09-01  1:38                                         ` Vladimir Oltean
2021-09-01  2:19                                           ` Saravana Kannan
2021-09-01  9:02                                             ` Vladimir Oltean
2021-09-01 22:57                                               ` Saravana Kannan
2021-09-01  2:00                                       ` Saravana Kannan
2021-09-01  8:46                                         ` Vladimir Oltean
2021-09-01 22:53                                           ` Saravana Kannan
2021-09-02 17:41                                           ` Andrew Lunn
2021-09-02 17:58                                             ` Saravana Kannan
2021-09-30  5:33                                       ` Saravana Kannan
2021-09-30 13:15                                         ` Andrew Lunn
2021-09-30 13:43                                         ` Vladimir Oltean
2021-09-30 14:00                                           ` Andrew Lunn
2021-09-30 17:31                                             ` Saravana Kannan
2021-09-30 19:38                                               ` Andrew Lunn
2021-09-30 19:48                                                 ` Saravana Kannan
2021-09-30 20:06                                                   ` Florian Fainelli
2021-09-30 20:14                                                     ` Saravana Kannan
2021-09-30 21:16                                                       ` Florian Fainelli
2021-09-30 20:22                                                     ` Andrew Lunn
2021-09-01  1:46                                     ` Saravana Kannan
2021-08-31 23:18                                   ` Andrew Lunn
2021-09-08 18:35                             ` Saravana Kannan
2021-09-09  1:39                           ` Andrew Lunn
2021-09-09  3:21                             ` Saravana Kannan
2021-09-09 10:38                               ` Vladimir Oltean
2021-09-09 15:00                               ` Andrew Lunn
2021-09-09 16:56                             ` Florian Fainelli
2021-08-26  7:45 ` [PATCH v1 2/2] net: dsa: rtl8366rb: Quick fix to work with fw_devlink=on Saravana Kannan
2021-08-26  7:55   ` Greg Kroah-Hartman
2021-08-26 11:25   ` Florian Fainelli
2021-08-26 17:29     ` Saravana Kannan
2021-08-26 11:29   ` Alvin Šipraga
2021-08-26 17:26     ` Saravana Kannan
2021-08-26 18:04       ` Alvin Šipraga

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