From: Russell King (Oracle) rmk+kernel@armlinux.org.uk
[ Upstream commit cc941e548bffc01b5816b4edc5cb432a137a58b3 ]
Uwe reports: "Most PHYs signal WoL using an interrupt. So disabling interrupts [at shutdown] breaks WoL at least on PHYs covered by the marvell driver."
Discussing with Ioana, the problem which was trying to be solved was: "The board in question is a LS1021ATSN which has two AR8031 PHYs that share an interrupt line. In case only one of the PHYs is probed and there are pending interrupts on the PHY#2 an IRQ storm will happen since there is no entity to clear the interrupt from PHY#2's registers. PHY#1's driver will get stuck in .handle_interrupt() indefinitely."
Further confirmation that "the two AR8031 PHYs are on the same MDIO bus."
With WoL using interrupts to wake the system, in such a case, the system will begin booting with an asserted interrupt. Thus, we need to cope with an interrupt asserted during boot.
Solve this instead by disabling interrupts during PHY probe. This will ensure in Ioana's situation that both PHYs of the same type sharing an interrupt line on a common MDIO bus will have their interrupt outputs disabled when the driver probes the device, but before we hook in any interrupt handlers - thus avoiding the interrupt storm.
A better fix would be for platform firmware to disable the interrupting devices at source during boot, before control is handed to the kernel.
Fixes: e2f016cf7751 ("net: phy: add a shutdown procedure") Link: 20230804071757.383971-1-u.kleine-koenig@pengutronix.de Reported-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Reviewed-by: Andrew Lunn andrew@lunn.ch Reviewed-by: Florian Fainelli florian.fainelli@broadcom.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/phy_device.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 2c4e6de8f4d9f..7958ea0e8714a 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -3217,6 +3217,8 @@ static int phy_probe(struct device *dev) goto out; }
+ phy_disable_interrupts(phydev); + /* Start out supporting everything. Eventually, * a controller will attach, and may modify one * or both of these values @@ -3334,16 +3336,6 @@ static int phy_remove(struct device *dev) return 0; }
-static void phy_shutdown(struct device *dev) -{ - struct phy_device *phydev = to_phy_device(dev); - - if (phydev->state == PHY_READY || !phydev->attached_dev) - return; - - phy_disable_interrupts(phydev); -} - /** * phy_driver_register - register a phy_driver with the PHY layer * @new_driver: new phy_driver to register @@ -3377,7 +3369,6 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner) new_driver->mdiodrv.driver.bus = &mdio_bus_type; new_driver->mdiodrv.driver.probe = phy_probe; new_driver->mdiodrv.driver.remove = phy_remove; - new_driver->mdiodrv.driver.shutdown = phy_shutdown; new_driver->mdiodrv.driver.owner = owner; new_driver->mdiodrv.driver.probe_type = PROBE_FORCE_SYNCHRONOUS;