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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>
This commit is contained in:
Heiner Kallweit 2021-04-07 17:51:56 +02:00 committed by Jakub Kicinski
parent a7150e3822
commit fba863b816
2 changed files with 8 additions and 0 deletions
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6
drivers/net/phy/phy_device.c
View File

@ -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;

2
include/linux/phy.h
View File

@ -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 */