net: phy: Make sure phy_start() always re-enables the phy interrupts

This is an alternative way of fixing:
 commit db9683fb412d ("net: phy: Make sure PHY_RESUMING state change
                      is always processed")

When the PHY state transitions from PHY_HALTED to PHY_RESUMING, there are
two things we need to do:
1). Re-enable interrupts (and power up the physical link, if powered down)
2). Update the PHY state and net-device based on the link status.

There's no strict reason why #1 has to be done from within the main
phy_state_machine() function. There is a risk that other changes to the
PHY (e.g. setting speed/duplex, which calls phy_start_aneg()) could cause
a subsequent state transition before phy_state_machine() has processed
the PHY_RESUMING state change. This would leave the PHY with interrupts
disabled and/or still in the BMCR_PDOWN/low-power mode.

Moving enabling the interrupts and phy_resume() into phy_start() will
guarantee this work always gets done. As the PHY is already in the HALTED
state and interrupts are disabled, it shouldn't conflict with any work
being done in phy_state_machine(). The downside of this change is that if
the PHY_RESUMING state is ever entered from anywhere else, it'll also have
to repeat this work.

Signed-off-by: Tim Beale <tim.beale@alliedtelesis.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 13 deletions

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 710696d1af97..47cd578052fc 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -465,7 +465,7 @@ int phy_start_aneg(struct phy_device *phydev)
         if (err < 0)
                 goto out_unlock;
 
-        if (phydev->state != PHY_HALTED && phydev->state != PHY_RESUMING) {
+        if (phydev->state != PHY_HALTED) {
                 if (AUTONEG_ENABLE == phydev->autoneg) {
                         phydev->state = PHY_AN;
                         phydev->link_timeout = PHY_AN_TIMEOUT;
@@ -742,6 +742,9 @@ EXPORT_SYMBOL(phy_stop);
  */
 void phy_start(struct phy_device *phydev)
 {
+        bool do_resume = false;
+        int err = 0;
+
         mutex_lock(&phydev->lock);
 
         switch (phydev->state) {
@@ -752,11 +755,22 @@ void phy_start(struct phy_device *phydev)
                 phydev->state = PHY_UP;
                 break;
         case PHY_HALTED:
+                /* make sure interrupts are re-enabled for the PHY */
+                err = phy_enable_interrupts(phydev);
+                if (err < 0)
+                        break;
+
                 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);
 }
 EXPORT_SYMBOL(phy_start);
 
@@ -769,7 +783,7 @@ void phy_state_machine(struct work_struct *work)
         struct delayed_work *dwork = to_delayed_work(work);
         struct phy_device *phydev =
                         container_of(dwork, struct phy_device, state_queue);
-        bool needs_aneg = false, do_suspend = false, do_resume = false;
+        bool needs_aneg = false, do_suspend = false;
         int err = 0;
 
         mutex_lock(&phydev->lock);
@@ -888,14 +902,6 @@ void phy_state_machine(struct work_struct *work)
                 }
                 break;
         case PHY_RESUMING:
-                err = phy_clear_interrupt(phydev);
-                if (err)
-                        break;
-
-                err = phy_config_interrupt(phydev, PHY_INTERRUPT_ENABLED);
-                if (err)
-                        break;
-
                 if (AUTONEG_ENABLE == phydev->autoneg) {
                         err = phy_aneg_done(phydev);
                         if (err < 0)
@@ -933,7 +939,6 @@ void phy_state_machine(struct work_struct *work)
                         }
                         phydev->adjust_link(phydev->attached_dev);
                 }
-                do_resume = true;
                 break;
         }
 
@@ -943,8 +948,6 @@ void phy_state_machine(struct work_struct *work)
                 err = phy_start_aneg(phydev);
         else if (do_suspend)
                 phy_suspend(phydev);
-        else if (do_resume)
-                phy_resume(phydev);
 
         if (err < 0)
                 phy_error(phydev);