net: phy: Improved PHY error reporting in state machine

When the PHY library calls phy_error() something bad has happened, and
we halt the PHY state machine. Calling phy_error() from the main state
machine however is not precise enough to know whether the issue is
reading the link status or starting auto-negotiation.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -1169,6 +1169,22 @@ void phy_stop_machine(struct phy_device *phydev)
 	mutex_unlock(&phydev->lock);
 }
 
+static void phy_process_error(struct phy_device *phydev)
+{
+	mutex_lock(&phydev->lock);
+	phydev->state = PHY_HALTED;
+	mutex_unlock(&phydev->lock);
+
+	phy_trigger_machine(phydev);
+}
+
+static void phy_error_precise(struct phy_device *phydev,
+			      const void *func, int err)
+{
+	WARN(1, "%pS: returned: %d\n", func, err);
+	phy_process_error(phydev);
+}
+
 /**
  * phy_error - enter HALTED state for this PHY device
  * @phydev: target phy_device struct
@@ -1181,12 +1197,7 @@ void phy_stop_machine(struct phy_device *phydev)
 void phy_error(struct phy_device *phydev)
 {
 	WARN_ON(1);
-
-	mutex_lock(&phydev->lock);
-	phydev->state = PHY_HALTED;
-	mutex_unlock(&phydev->lock);
-
-	phy_trigger_machine(phydev);
+	phy_process_error(phydev);
 }
 EXPORT_SYMBOL(phy_error);
 
@@ -1378,6 +1389,7 @@ void phy_state_machine(struct work_struct *work)
 	struct net_device *dev = phydev->attached_dev;
 	bool needs_aneg = false, do_suspend = false;
 	enum phy_state old_state;
+	const void *func = NULL;
 	bool finished = false;
 	int err = 0;
 
@@ -1396,6 +1408,7 @@ void phy_state_machine(struct work_struct *work)
 	case PHY_NOLINK:
 	case PHY_RUNNING:
 		err = phy_check_link_status(phydev);
+		func = &phy_check_link_status;
 		break;
 	case PHY_CABLETEST:
 		err = phydev->drv->cable_test_get_status(phydev, &finished);
@@ -1425,16 +1438,18 @@ void phy_state_machine(struct work_struct *work)
 
 	mutex_unlock(&phydev->lock);
 
-	if (needs_aneg)
+	if (needs_aneg) {
 		err = phy_start_aneg(phydev);
-	else if (do_suspend)
+		func = &phy_start_aneg;
+	} else if (do_suspend) {
 		phy_suspend(phydev);
+	}
 
 	if (err == -ENODEV)
 		return;
 
 	if (err < 0)
-		phy_error(phydev);
+		phy_error_precise(phydev, func, err);
 
 	if (old_state != phydev->state) {
 		phydev_dbg(phydev, "PHY state change %s -> %s\n",