Merge branch 'net-make-phy-pm-ops-a-no-op-if-mac-driver-manages-phy-pm'

Heiner Kallweit says:

====================
net: 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.
====================

Link: https://lore.kernel.org/r/9e695411-ab1d-34fe-8b90-3e8192ab84f6@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/fec_main.c

@@ -2048,6 +2048,8 @@ static int fec_enet_mii_probe(struct net_device *ndev)
 	fep->link = 0;
 	fep->full_duplex = 0;
 
+	phy_dev->mac_managed_pm = 1;
+
 	phy_attached_info(phy_dev);
 
 	return 0;
@@ -3864,6 +3866,7 @@ static int __maybe_unused fec_resume(struct device *dev)
 		netif_device_attach(ndev);
 		netif_tx_unlock_bh(ndev);
 		napi_enable(&fep->napi);
+		phy_init_hw(ndev->phydev);
 		phy_start(ndev->phydev);
 	}
 	rtnl_unlock();

drivers/net/ethernet/realtek/r8169_main.c

@@ -4660,6 +4660,7 @@ static void rtl8169_down(struct rtl8169_private *tp)
 static void rtl8169_up(struct rtl8169_private *tp)
 {
 	pci_set_master(tp->pci_dev);
+	phy_init_hw(tp->phydev);
 	phy_resume(tp->phydev);
 	rtl8169_init_phy(tp);
 	napi_enable(&tp->napi);
@@ -5085,6 +5086,8 @@ static int r8169_mdio_register(struct rtl8169_private *tp)
 		return -EUNATCH;
 	}
 
+	tp->phydev->mac_managed_pm = 1;
+
 	/* PHY will be woken up in rtl_open() */
 	phy_suspend(tp->phydev);
 

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;
 

include/linux/phy.h

@@ -493,6 +493,7 @@ struct macsec_ops;
  * @loopback_enabled: Set true if this PHY has been loopbacked successfully.
  * @downshifted_rate: Set true if link speed has been downshifted.
  * @is_on_sfp_module: Set true if PHY is located on an SFP module.
+ * @mac_managed_pm: Set true if MAC driver takes of suspending/resuming PHY
  * @state: State of the PHY for management purposes
  * @dev_flags: Device-specific flags used by the PHY driver.
  * @irq: IRQ number of the PHY's interrupt (-1 if none)
@@ -567,6 +568,7 @@ struct phy_device {
 	unsigned loopback_enabled:1;
 	unsigned downshifted_rate:1;
 	unsigned is_on_sfp_module:1;
+	unsigned mac_managed_pm:1;
 
 	unsigned autoneg:1;
 	/* The most recently read link state */