When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes to other registers, or reset the registers to power-on defaults. Micrel PHYs do this for their interrupt registers.

The current structure of phylib tries to enable interrupts before resuming (and releasing) the BMCR_PDOWN bit. This fails, causing Micrel PHYs to stop working after a suspend/resume sequence if they are using interrupts.

Fix this by ensuring that the PHY driver resume methods do not take the phydev->lock mutex themselves, but the callers of phy_resume() take that lock. This then allows us to move the call to phy_resume() before we enable interrupts in phy_start().

Signed-off-by Russell King <[email protected]>

Reviewed-by Andrew Lunn <[email protected]>

Signed-off-by David S. Miller <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/net/phy/at803x.c     |    4 ----
 drivers/net/phy/phy.c        |    9 +++------
 drivers/net/phy/phy_device.c |   10 ++++++----
 3 files changed, 9 insertions(+), 14 deletions(-)

drivers/net/phy/at803x.c +0 -4

@@ -239,14 +239,10 @@ static int at803x_resume(struct phy_devi
 {
 	int value;
 
-	mutex_lock(&phydev->lock);
-
 	value = phy_read(phydev, MII_BMCR);
 	value &= ~(BMCR_PDOWN | BMCR_ISOLATE);
 	phy_write(phydev, MII_BMCR, value);
 
-	mutex_unlock(&phydev->lock);
-
 	return 0;
 }

drivers/net/phy/phy.c +3 -6

@@ -828,7 +828,6 @@ EXPORT_SYMBOL(phy_stop);
  */
 void phy_start(struct phy_device *phydev)
 {
-	bool do_resume = false;
 	int err = 0;
 
 	mutex_lock(&phydev->lock);

@@ -841,6 +840,9 @@ void phy_start(struct phy_device *phydev
 		phydev->state = PHY_UP;
 		break;
 	case PHY_HALTED:
+		/* if phy was suspended, bring the physical link up again */
+		phy_resume(phydev);
+
 		/* make sure interrupts are re-enabled for the PHY */
 		if (phydev->irq != PHY_POLL) {
 			err = phy_enable_interrupts(phydev);

@@ -849,17 +851,12 @@ void phy_start(struct phy_device *phydev
 		}
 
 		phydev->state = PHY_RESUMING;
-		do_resume = true;
 		break;
 	default:
 		break;
 	}
 	mutex_unlock(&phydev->lock);
 
-	/* if phy was suspended, bring the physical link up again */
-	if (do_resume)
-		phy_resume(phydev);
-
 	phy_trigger_machine(phydev, true);
 }
 EXPORT_SYMBOL(phy_start);

drivers/net/phy/phy_device.c +6 -4

@@ -135,7 +135,9 @@ static int mdio_bus_phy_resume(struct de
 	if (!mdio_bus_phy_may_suspend(phydev))
 		goto no_resume;
 
+	mutex_lock(&phydev->lock);
 	ret = phy_resume(phydev);
+	mutex_unlock(&phydev->lock);
 	if (ret < 0)
 		return ret;

@@ -1026,7 +1028,9 @@ int phy_attach_direct(struct net_device
 	if (err)
 		goto error;
 
+	mutex_lock(&phydev->lock);
 	phy_resume(phydev);
+	mutex_unlock(&phydev->lock);
 	phy_led_triggers_register(phydev);
 
 	return err;

@@ -1157,6 +1161,8 @@ int phy_resume(struct phy_device *phydev
 	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
 	int ret = 0;
 
+	WARN_ON(!mutex_is_locked(&phydev->lock));
+
 	if (phydev->drv && phydrv->resume)
 		ret = phydrv->resume(phydev);

@@ -1639,13 +1645,9 @@ int genphy_resume(struct phy_device *phy
 {
 	int value;
 
-	mutex_lock(&phydev->lock);
-
 	value = phy_read(phydev, MII_BMCR);
 	phy_write(phydev, MII_BMCR, value & ~BMCR_PDOWN);
 
-	mutex_unlock(&phydev->lock);
-
 	return 0;
 }
 EXPORT_SYMBOL(genphy_resume);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/arm-8731-1-fix-csum_partial_copy_from_user-stack-mismatch.patch queue-4.14/net-phy-fix-resume-handling.patch

Andrew Lunn

maintainer

2018-02-28 15:44 UTC #1 lore raw

Quoted 9 lines

When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes to other registers, or reset the registers to power-on defaults. Micrel PHYs do this for their interrupt registers.
The current structure of phylib tries to enable interrupts before resuming (and releasing) the BMCR_PDOWN bit. This fails, causing Micrel PHYs to stop working after a suspend/resume sequence if they are using interrupts.

Quoted 4 lines

Fix this by ensuring that the PHY driver resume methods do not take the phydev->lock mutex themselves, but the callers of phy_resume() take that lock. This then allows us to move the call to phy_resume() before we enable interrupts in phy_start().

Hi Greg

This patch introduces some issues. You don't want this patch on its own, you want it in combination with:

Fixes 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")

Which went into David Millers net tree yesterday and should be making its way towards stable.

I suggest you hold off on this patch, until you can do both at the same time.

Andrew

Greg KH

author maintainer

2018-02-28 16:27 UTC #2 lore raw

Quoted 19 lines · Andrew Lunn

Quoted 9 lines
When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes to other registers, or reset the registers to power-on defaults. Micrel PHYs do this for their interrupt registers.
The current structure of phylib tries to enable interrupts before resuming (and releasing) the BMCR_PDOWN bit. This fails, causing Micrel PHYs to stop working after a suspend/resume sequence if they are using interrupts.
Quoted 4 lines
Fix this by ensuring that the PHY driver resume methods do not take the phydev->lock mutex themselves, but the callers of phy_resume() take that lock. This then allows us to move the call to phy_resume() before we enable interrupts in phy_start().
Hi Greg
This patch introduces some issues. You don't want this patch on its own, you want it in combination with:

Quoted 7 lines

Fixes 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")
Which went into David Millers net tree yesterday and should be making its way towards stable.
I suggest you hold off on this patch, until you can do both at the same time.

Thanks for letting me know, I've now dropped this.

greg k-h

Greg KH

author maintainer

2018-03-16 12:38 UTC #3 lore raw

Quoted 22 lines · Greg KH

Quoted 21 lines · Andrew Lunn
Quoted 9 lines
When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes to other registers, or reset the registers to power-on defaults. Micrel PHYs do this for their interrupt registers.
The current structure of phylib tries to enable interrupts before resuming (and releasing) the BMCR_PDOWN bit. This fails, causing Micrel PHYs to stop working after a suspend/resume sequence if they are using interrupts.
Quoted 4 lines
Fix this by ensuring that the PHY driver resume methods do not take the phydev->lock mutex themselves, but the callers of phy_resume() take that lock. This then allows us to move the call to phy_resume() before we enable interrupts in phy_start().
Hi Greg
This patch introduces some issues. You don't want this patch on its own, you want it in combination with:
Fixes 9c2c2e62df3f ("net: phy: Restore phy_resume() locking assumption")

Quoted 7 lines

Quoted 5 lines
Which went into David Millers net tree yesterday and should be making its way towards stable.
I suggest you hold off on this patch, until you can do both at the same time.
Thanks for letting me know, I've now dropped this.

And now both are queued up for 4.14.y, thanks.

greg k-h