netdev - Re: [PATCH] net: phy: Trigger link_change_notify on PHY

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Date:   Wed, 6 Jan 2021 00:11:15 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Marek Vasut <marex@...x.de>, Andrew Lunn <andrew@...n.ch>,
        Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] net: phy: Trigger link_change_notify on PHY_HALTED

On 05.01.2021 17:11, Marek Vasut wrote:
> In case the PHY transitions to PHY_HALTED state in phy_stop(), the
> link_change_notify callback is not triggered. That's because the
> phydev->state = PHY_HALTED in phy_stop() is assigned first, and
> phy_state_machine() is called afterward. For phy_state_machine(),
> no state transition happens, because old_state = PHY_HALTED and
> phy_dev->state = PHY_HALTED.
> 
> Signed-off-by: Marek Vasut <marex@...x.de>
> Cc: Andrew Lunn <andrew@...n.ch>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: Heiner Kallweit <hkallweit1@...il.com>
> ---
>  drivers/net/phy/phy.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 45f75533c47c..fca8c3eebc5d 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1004,6 +1004,7 @@ EXPORT_SYMBOL(phy_free_interrupt);
>  void phy_stop(struct phy_device *phydev)
>  {
>  	struct net_device *dev = phydev->attached_dev;
> +	enum phy_state old_state;
>  
>  	if (!phy_is_started(phydev) && phydev->state != PHY_DOWN) {
>  		WARN(1, "called from state %s\n",
> @@ -1021,8 +1022,17 @@ void phy_stop(struct phy_device *phydev)
>  	if (phydev->sfp_bus)
>  		sfp_upstream_stop(phydev->sfp_bus);
>  
> +	old_state = phydev->state;
>  	phydev->state = PHY_HALTED;
>  
> +	if (old_state != phydev->state) {
> +		phydev_err(phydev, "PHY state change %s -> %s\n",
> +			   phy_state_to_str(old_state),
> +			   phy_state_to_str(phydev->state));
> +		if (phydev->drv && phydev->drv->link_change_notify)
> +			phydev->drv->link_change_notify(phydev);
> +	}
> +
>  	mutex_unlock(&phydev->lock);
>  
>  	phy_state_machine(&phydev->state_queue.work);
> 

Following is RFC as an additional idea. When requesting a new state
from outside the state machine, we could simply provide the old
state to the state machine in a new phy_device member.
Then we shouldn't have to touch phy_stop(), and maybe phy_error().
And it looks cleaner to me than duplicating code from the state
machine to functions like phy_stop().

---
 drivers/net/phy/phy.c        | 10 +++++++++-
 drivers/net/phy/phy_device.c |  1 +
 include/linux/phy.h          |  3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 45f75533c..347e42d90 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -45,6 +45,7 @@ static const char *phy_state_to_str(enum phy_state st)
 {
 	switch (st) {
 	PHY_STATE_STR(DOWN)
+	PHY_STATE_STR(INVALID)
 	PHY_STATE_STR(READY)
 	PHY_STATE_STR(UP)
 	PHY_STATE_STR(RUNNING)
@@ -1021,6 +1022,7 @@ void phy_stop(struct phy_device *phydev)
 	if (phydev->sfp_bus)
 		sfp_upstream_stop(phydev->sfp_bus);
 
+	phydev->old_state = phydev->state;
 	phydev->state = PHY_HALTED;
 
 	mutex_unlock(&phydev->lock);
@@ -1086,7 +1088,13 @@ void phy_state_machine(struct work_struct *work)
 
 	mutex_lock(&phydev->lock);
 
-	old_state = phydev->state;
+	/* set if a new state is requested from outside the state machine */
+	if (phydev->old_state != PHY_INVALID) {
+		old_state = phydev->old_state;
+		phydev->old_state = PHY_INVALID;
+	} else {
+		old_state = phydev->state;
+	}
 
 	switch (phydev->state) {
 	case PHY_DOWN:
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 80c2e646c..9f8d9f68b 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -620,6 +620,7 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, u32 phy_id,
 	device_initialize(&mdiodev->dev);
 
 	dev->state = PHY_DOWN;
+	dev->old_state = PHY_INVALID;
 
 	mutex_init(&dev->lock);
 	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 9effb511a..df48ea88c 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -442,6 +442,7 @@ struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
  */
 enum phy_state {
 	PHY_DOWN = 0,
+	PHY_INVALID,
 	PHY_READY,
 	PHY_HALTED,
 	PHY_UP,
@@ -566,6 +567,8 @@ struct phy_device {
 	unsigned interrupts:1;
 
 	enum phy_state state;
+	/* if a new state is requested from outside the state machine */
+	enum phy_state old_state;
 
 	u32 dev_flags;
 
-- 
2.30.0