[PATCH net v5 3/4] net: phy: stop postponing PHY interrupts when a PHY PM callback fails

[Igor Velkov via B4 Relay]

From: Igor Velkov <iav@xxxxxx>

When phy_suspend() fails in mdio_bus_phy_suspend(), irq_suspended
stays set and the state machine stays stopped: the PM core does not
resume a device whose suspend callback failed, and the next PHY
interrupt disables the line until the next resume. When phy_init_hw()
or phy_resume() fail, mdio_bus_phy_resume() returns before the rerun,
with irq_suspended set and a postponed interrupt left disabled.

Undo the postponing and restart the state machine when phy_suspend()
fails. When phy_init_hw() or phy_resume() fail, stop postponing too, but
leave a line that a postponed interrupt disabled off, as before this
patch: the PHY may be out of reach, and its handler could not quiet a
level-triggered source. The line comes back on the next successful
resume; phy_free_interrupt() gives it back to the other users of a
shared line, and a new request restarts it.

Fixes: 1758bde2e4aa ("net: phy: Don't trigger state machine while in suspend")
Signed-off-by: Igor Velkov <iav@xxxxxx>
---
Haoning Cheng's Tested-by on v4 is not carried: a failed resume now
leaves the line disabled.
---
 drivers/net/phy/phy.c        |  2 +-
 drivers/net/phy/phy_device.c | 29 ++++++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index ea22ebb14a83..62b7f428f9da 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -1414,7 +1414,7 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
 	irqreturn_t ret;
 
 	/* Wakeup interrupts may occur during a system sleep transition.
-	 * Postpone handling until the PHY has resumed.
+	 * Postpone handling until the transition ends.
 	 */
 	if (IS_ENABLED(CONFIG_PM_SLEEP) && READ_ONCE(phydev->irq_suspended)) {
 		struct net_device *netdev = phydev->attached_dev;
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index d3815ee21541..110c9dfcbd91 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -333,8 +333,8 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 }
 
 /* Wakeup interrupts may occur during the system sleep transition when
- * the PHY is inaccessible. Set flag to postpone handling until the PHY
- * has resumed. Wait for concurrent interrupt handler to complete.
+ * the PHY is inaccessible. Set flag to postpone handling until the
+ * transition ends. Wait for concurrent interrupt handler to complete.
  */
 static __maybe_unused void mdio_bus_phy_suspend_irq(struct phy_device *phydev)
 {
@@ -367,6 +367,7 @@ static __maybe_unused void mdio_bus_phy_resume_irq(struct phy_device *phydev)
 static __maybe_unused int mdio_bus_phy_suspend(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
+	int ret;
 
 	if (phydev->mac_managed_pm)
 		return 0;
@@ -384,9 +385,20 @@ static __maybe_unused int mdio_bus_phy_suspend(struct device *dev)
 	if (!mdio_bus_phy_may_suspend(phydev))
 		return 0;
 
+	ret = phy_suspend(phydev);
+	if (ret) {
+		/* The PM core skips the resume callback of a device whose
+		 * suspend callback failed.
+		 */
+		mdio_bus_phy_resume_irq(phydev);
+		if (phy_uses_state_machine(phydev))
+			phy_start_machine(phydev);
+		return ret;
+	}
+
 	phydev->suspended_by_mdio_bus = 1;
 
-	return phy_suspend(phydev);
+	return 0;
 }
 
 static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
@@ -412,11 +424,11 @@ static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
 
 	ret = phy_init_hw(phydev);
 	if (ret < 0)
-		return ret;
+		goto err;
 
 	ret = phy_resume(phydev);
 	if (ret < 0)
-		return ret;
+		goto err;
 no_resume:
 	mdio_bus_phy_resume_irq(phydev);
 
@@ -424,6 +436,13 @@ static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
 		phy_start_machine(phydev);
 
 	return 0;
+
+err:
+	/* Stop postponing, but leave a line that a postponed interrupt
+	 * disabled off: its handler may not reach a PHY that did not resume.
+	 */
+	WRITE_ONCE(phydev->irq_suspended, false);
+	return ret;
 }
 
 static SIMPLE_DEV_PM_OPS(mdio_bus_phy_pm_ops, mdio_bus_phy_suspend,

-- 
2.43.0