net: phy: make PHY PM ops a no-op if MAC driver manages PHY PM

Resume callback of the PHY driver is called after the one for the MAC
driver. The PHY driver resume callback calls phy_init_hw(), and this is
potentially problematic if the MAC driver calls phy_start() in its resume
callback. One issue was reported with the fec driver and a KSZ8081 PHY
which seems to become unstable if a soft reset is triggered during aneg.

The new flag allows MAC drivers to indicate that they take care of
suspending/resuming the PHY. Then the MAC PM callbacks can handle
any dependency between MAC and PHY PM.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a009d1769b08..73d29fd5e03d 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -273,6 +273,9 @@ static __maybe_unused int mdio_bus_phy_suspend(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 
+	if (phydev->mac_managed_pm)
+		return 0;
+
 	/* We must stop the state machine manually, otherwise it stops out of
 	 * control, possibly with the phydev->lock held. Upon resume, netdev
 	 * may call phy routines that try to grab the same lock, and that may
@@ -294,6 +297,9 @@ static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
 	struct phy_device *phydev = to_phy_device(dev);
 	int ret;
 
+	if (phydev->mac_managed_pm)
+		return 0;
+
 	if (!phydev->suspended_by_mdio_bus)
 		goto no_resume;