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
next prev parent 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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