PHY_HALTED and PHY_READY both are non-started states and quite similar.
Major difference is that phy_start() changes from PHY_HALTED to
PHY_RESUMING which doesn't reconfigure aneg (what PHY_UP does).

There's no guarantee that PHY registers are completely untouched when
waking up from power-down, e.g. after system suspend. Therefore it's
safer to reconfigure aneg also when starting from PHY_HALTED. This can
be achieved and state machine made simpler by making PHY_HALTED going
to PHY_READY after having stopped everything. Then the only way up is
over PHY_UP. Also let's warn in phy_start() if it's called from a
state other than PHY_READY.
As part of the change PHY_HALTED is renamed to PHY_HALT to reflect that
it is a transition state.

Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
---
 drivers/net/phy/phy.c | 41 +++++++++++++++++------------------------
 include/linux/phy.h   | 16 ++++++++--------
 2 files changed, 25 insertions(+), 32 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index d33e7b3ca..2a69d947e 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -47,12 +47,12 @@ static const char *phy_state_to_str(enum phy_state st)
        switch (st) {
        PHY_STATE_STR(DOWN)
        PHY_STATE_STR(READY)
+       PHY_STATE_STR(HALT)
        PHY_STATE_STR(UP)
        PHY_STATE_STR(RUNNING)
        PHY_STATE_STR(NOLINK)
        PHY_STATE_STR(FORCING)
        PHY_STATE_STR(CHANGELINK)
-       PHY_STATE_STR(HALTED)
        PHY_STATE_STR(RESUMING)
        }
 
@@ -733,7 +733,7 @@ static void phy_error(struct phy_device *phydev)
        WARN_ON(1);
 
        mutex_lock(&phydev->lock);
-       phydev->state = PHY_HALTED;
+       phydev->state = PHY_HALT;
        mutex_unlock(&phydev->lock);
 
        phy_trigger_machine(phydev);
@@ -859,16 +859,11 @@ void phy_stop(struct phy_device *phydev)
        if (phy_interrupt_is_valid(phydev))
                phy_disable_interrupts(phydev);
 
-       phydev->state = PHY_HALTED;
+       phydev->state = PHY_HALT;
 
        mutex_unlock(&phydev->lock);
 
        phy_state_machine(&phydev->state_queue.work);
-
-       /* Cannot call flush_scheduled_work() here as desired because
-        * of rtnl_lock(), but PHY_HALTED shall guarantee irq handler
-        * will not reenable interrupts.
-        */
 }
 EXPORT_SYMBOL(phy_stop);
 
@@ -888,29 +883,26 @@ void phy_start(struct phy_device *phydev)
 
        mutex_lock(&phydev->lock);
 
-       switch (phydev->state) {
-       case PHY_READY:
-               phydev->state = PHY_UP;
-               break;
-       case PHY_HALTED:
+       if (phydev->state == PHY_READY) {
                /* if phy was suspended, bring the physical link up again */
                __phy_resume(phydev);
 
                /* make sure interrupts are re-enabled for the PHY */
                if (phy_interrupt_is_valid(phydev)) {
                        err = phy_enable_interrupts(phydev);
-                       if (err < 0)
-                               break;
+                       if (err < 0) {
+                               WARN_ON(1);
+                               goto out;
+                       }
                }
-
-               phydev->state = PHY_RESUMING;
-               break;
-       default:
-               break;
+               phydev->state = PHY_UP;
+               phy_trigger_machine(phydev);
+       } else {
+               WARN(1, "called from state %s\n",
+                    phy_state_to_str(phydev->state));
        }
+out:
        mutex_unlock(&phydev->lock);
-
-       phy_trigger_machine(phydev);
 }
 EXPORT_SYMBOL(phy_start);
 
@@ -962,12 +954,13 @@ void phy_state_machine(struct work_struct *work)
                        phy_link_down(phydev, false);
                }
                break;
-       case PHY_HALTED:
+       case PHY_HALT:
                if (phydev->link) {
                        phydev->link = 0;
                        phy_link_down(phydev, true);
                        do_suspend = true;
                }
+               phydev->state = PHY_READY;
                break;
        }
 
@@ -990,7 +983,7 @@ void phy_state_machine(struct work_struct *work)
         * PHY, if PHY_IGNORE_INTERRUPT is set, then we will be moving
         * between states from phy_mac_interrupt().
         *
-        * In state PHY_HALTED the PHY gets suspended, so rescheduling the
+        * In state PHY_HALT the PHY gets suspended, so rescheduling the
         * state machine would be pointless and possibly error prone when
         * called from phy_disconnect() synchronously.
         */
diff --git a/include/linux/phy.h b/include/linux/phy.h
index da039f211..21e553f51 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -288,38 +288,38 @@ struct phy_device *mdiobus_scan(struct mii_bus *bus, int 
addr);
  *
  * NOLINK: PHY is up, but not currently plugged in.
  * - irq or timer will set RUNNING if link comes back
- * - phy_stop moves to HALTED
+ * - phy_stop moves to HALT
  *
  * FORCING: PHY is being configured with forced settings
  * - if link is up, move to RUNNING
  * - If link is down, we drop to the next highest setting, and
  *   retry (FORCING) after a timeout
- * - phy_stop moves to HALTED
+ * - phy_stop moves to HALT
  *
  * RUNNING: PHY is currently up, running, and possibly sending
  * and/or receiving packets
  * - irq or timer will set NOLINK if link goes down
- * - phy_stop moves to HALTED
+ * - phy_stop moves to HALT
  *
  * CHANGELINK: PHY experienced a change in link state
  * - timer moves to RUNNING if link
  * - timer moves to NOLINK if the link is down
- * - phy_stop moves to HALTED
+ * - phy_stop moves to HALT
  *
- * HALTED: PHY is up, but no polling or interrupts are done. Or
+ * HALT: PHY is up, but no polling or interrupts are done. Or
  * PHY is in an error state.
  *
- * - phy_start moves to RESUMING
+ * - moves to READY
  *
  * RESUMING: PHY was halted, but now wants to run again.
  * - If we are forcing, or aneg is done, timer moves to RUNNING
  * - If aneg is not done, timer moves to AN
- * - phy_stop moves to HALTED
+ * - phy_stop moves to HALT
  */
 enum phy_state {
        PHY_DOWN = 0,
        PHY_READY,
-       PHY_HALTED,
+       PHY_HALT,
        PHY_UP,
        PHY_RUNNING,
        PHY_NOLINK,
-- 
2.20.1


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