[PATCH net 0/2] net: stmmac: fix WoL issue

[PATCH net 0/2] net: stmmac: fix WoL issue

[Joakim Zhang]

This patch set fixes stmmac not working after system resume back with WoL
active. Thanks a lot for Russell King keeps looking into this issue.

Joakim Zhang (1):
  net: stmmac: fix MAC not working when system resume back with WoL
    active

Russell King (Oracle) (1):
  net: phylink: add suspend/resume support

 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 36 ++++----
 drivers/net/phy/phylink.c                     | 82 +++++++++++++++++++
 include/linux/phylink.h                       |  3 +
 3 files changed, 103 insertions(+), 18 deletions(-)

-- 
2.17.1

[PATCH net 1/2] net: phylink: add suspend/resume support

[Joakim Zhang]

From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>

Joakim Zhang reports that Wake-on-Lan with the stmmac ethernet driver broke
when moving the incorrect handling of mac link state out of mac_config().
This reason this breaks is because the stmmac's WoL is handled by the MAC
rather than the PHY, and phylink doesn't cater for that scenario.

This patch adds the necessary phylink code to handle suspend/resume events
according to whether the MAC still needs a valid link or not. This is the
barest minimum for this support.

Reported-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Tested-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
---
 drivers/net/phy/phylink.c | 82 +++++++++++++++++++++++++++++++++++++++
 include/linux/phylink.h   |  3 ++
 2 files changed, 85 insertions(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 2cdf9f989dec..a1464b764d4d 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -33,6 +33,7 @@
 enum {
 	PHYLINK_DISABLE_STOPPED,
 	PHYLINK_DISABLE_LINK,
+	PHYLINK_DISABLE_MAC_WOL,
 };
 
 /**
@@ -1282,6 +1283,9 @@ EXPORT_SYMBOL_GPL(phylink_start);
  * network device driver's &struct net_device_ops ndo_stop() method.  The
  * network device's carrier state should not be changed prior to calling this
  * function.
+ *
+ * This will synchronously bring down the link if the link is not already
+ * down (in other words, it will trigger a mac_link_down() method call.)
  */
 void phylink_stop(struct phylink *pl)
 {
@@ -1301,6 +1305,84 @@ void phylink_stop(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_stop);
 
+/**
+ * phylink_suspend() - handle a network device suspend event
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @mac_wol: true if the MAC needs to receive packets for Wake-on-Lan
+ *
+ * Handle a network device suspend event. There are several cases:
+ * - If Wake-on-Lan is not active, we can bring down the link between
+ *   the MAC and PHY by calling phylink_stop().
+ * - If Wake-on-Lan is active, and being handled only by the PHY, we
+ *   can also bring down the link between the MAC and PHY.
+ * - If Wake-on-Lan is active, but being handled by the MAC, the MAC
+ *   still needs to receive packets, so we can not bring the link down.
+ */
+void phylink_suspend(struct phylink *pl, bool mac_wol)
+{
+	ASSERT_RTNL();
+
+	if (mac_wol && (!pl->netdev || pl->netdev->wol_enabled)) {
+		/* Wake-on-Lan enabled, MAC handling */
+		mutex_lock(&pl->state_mutex);
+
+		/* Stop the resolver bringing the link up */
+		__set_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state);
+
+		/* Disable the carrier, to prevent transmit timeouts,
+		 * but one would hope all packets have been sent. This
+		 * also means phylink_resolve() will do nothing.
+		 */
+		netif_carrier_off(pl->netdev);
+
+		/* We do not call mac_link_down() here as we want the
+		 * link to remain up to receive the WoL packets.
+		 */
+		mutex_unlock(&pl->state_mutex);
+	} else {
+		phylink_stop(pl);
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_suspend);
+
+/**
+ * phylink_resume() - handle a network device resume event
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * Undo the effects of phylink_suspend(), returning the link to an
+ * operational state.
+ */
+void phylink_resume(struct phylink *pl)
+{
+	ASSERT_RTNL();
+
+	if (test_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state)) {
+		/* Wake-on-Lan enabled, MAC handling */
+
+		/* Call mac_link_down() so we keep the overall state balanced.
+		 * Do this under the state_mutex lock for consistency. This
+		 * will cause a "Link Down" message to be printed during
+		 * resume, which is harmless - the true link state will be
+		 * printed when we run a resolve.
+		 */
+		mutex_lock(&pl->state_mutex);
+		phylink_link_down(pl);
+		mutex_unlock(&pl->state_mutex);
+
+		/* Re-apply the link parameters so that all the settings get
+		 * restored to the MAC.
+		 */
+		phylink_mac_initial_config(pl, true);
+
+		/* Re-enable and re-resolve the link parameters */
+		clear_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state);
+		phylink_run_resolve(pl);
+	} else {
+		phylink_start(pl);
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_resume);
+
 /**
  * phylink_ethtool_get_wol() - get the wake on lan parameters for the PHY
  * @pl: a pointer to a &struct phylink returned from phylink_create()
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index afb3ded0b691..237291196ce2 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -451,6 +451,9 @@ void phylink_mac_change(struct phylink *, bool up);
 void phylink_start(struct phylink *);
 void phylink_stop(struct phylink *);
 
+void phylink_suspend(struct phylink *pl, bool mac_wol);
+void phylink_resume(struct phylink *pl);
+
 void phylink_ethtool_get_wol(struct phylink *, struct ethtool_wolinfo *);
 int phylink_ethtool_set_wol(struct phylink *, struct ethtool_wolinfo *);
 
-- 
2.17.1

[PATCH net 2/2] net: stmmac: fix MAC not working when system resume back with WoL active

[Joakim Zhang]

We can reproduce this issue with below steps:
1) enable WoL on the host
2) host system suspended
3) remote client send out wakeup packets
We can see that host system resume back, but can't work, such as ping failed.

After a bit digging, this issue is introduced by the commit 46f69ded988d
("net: stmmac: Use resolved link config in mac_link_up()"), which use
the finalised link parameters in mac_link_up() rather than the
parameters in mac_config().

There are two scenarios for MAC suspend/resume in STMMAC driver:

1) MAC suspend with WoL inactive, stmmac_suspend() call
phylink_mac_change() to notify phylink machine that a change in MAC
state, then .mac_link_down callback would be invoked. Further, it will
call phylink_stop() to stop the phylink instance. When MAC resume back,
firstly phylink_start() is called to start the phylink instance, then
call phylink_mac_change() which will finally trigger phylink machine to
invoke .mac_config and .mac_link_up callback. All is fine since
configuration in these two callbacks will be initialized, that means MAC
can restore the state.

2) MAC suspend with WoL active, phylink_mac_change() will put link
down, but there is no phylink_stop() to stop the phylink instance, so it
will link up again, that means .mac_config and .mac_link_up would be
invoked before system suspended. After system resume back, it will do
DMA initialization and SW reset which let MAC lost the hardware setting
(i.e MAC_Configuration register(offset 0x0) is reset). Since link is up
before system suspended, so .mac_link_up would not be invoked after
system resume back, lead to there is no chance to initialize the
configuration in .mac_link_up callback, as a result, MAC can't work any
longer.

After discussed with Russell King [1], we confirm that phylink framework
have not take WoL into consideration yet. This patch calls
phylink_suspend()/phylink_resume() functions which is newly introduced
by Russell King to fix this issue.

[1] https://lore.kernel.org/netdev/20210901090228.11308-1-qiangqing.zhang@nxp.com/

Fixes: 46f69ded988d ("net: stmmac: Use resolved link config in mac_link_up()")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 36 +++++++++----------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 97238359e101..ece02b35a6ce 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -7123,8 +7123,6 @@ int stmmac_suspend(struct device *dev)
 	if (!ndev || !netif_running(ndev))
 		return 0;
 
-	phylink_mac_change(priv->phylink, false);
-
 	mutex_lock(&priv->lock);
 
 	netif_device_detach(ndev);
@@ -7150,14 +7148,6 @@ int stmmac_suspend(struct device *dev)
 		stmmac_pmt(priv, priv->hw, priv->wolopts);
 		priv->irq_wake = 1;
 	} else {
-		mutex_unlock(&priv->lock);
-		rtnl_lock();
-		if (device_may_wakeup(priv->device))
-			phylink_speed_down(priv->phylink, false);
-		phylink_stop(priv->phylink);
-		rtnl_unlock();
-		mutex_lock(&priv->lock);
-
 		stmmac_mac_set(priv, priv->ioaddr, false);
 		pinctrl_pm_select_sleep_state(priv->device);
 		/* Disable clock in case of PWM is off */
@@ -7171,6 +7161,16 @@ int stmmac_suspend(struct device *dev)
 
 	mutex_unlock(&priv->lock);
 
+	rtnl_lock();
+	if (device_may_wakeup(priv->device) && priv->plat->pmt) {
+		phylink_suspend(priv->phylink, true);
+	} else {
+		if (device_may_wakeup(priv->device))
+			phylink_speed_down(priv->phylink, false);
+		phylink_suspend(priv->phylink, false);
+	}
+	rtnl_unlock();
+
 	if (priv->dma_cap.fpesel) {
 		/* Disable FPE */
 		stmmac_fpe_configure(priv, priv->ioaddr,
@@ -7261,13 +7261,15 @@ int stmmac_resume(struct device *dev)
 			return ret;
 	}
 
-	if (!device_may_wakeup(priv->device) || !priv->plat->pmt) {
-		rtnl_lock();
-		phylink_start(priv->phylink);
-		/* We may have called phylink_speed_down before */
-		phylink_speed_up(priv->phylink);
-		rtnl_unlock();
+	rtnl_lock();
+	if (device_may_wakeup(priv->device) && priv->plat->pmt) {
+		phylink_resume(priv->phylink);
+	} else {
+		phylink_resume(priv->phylink);
+		if (device_may_wakeup(priv->device))
+			phylink_speed_up(priv->phylink);
 	}
+	rtnl_unlock();
 
 	rtnl_lock();
 	mutex_lock(&priv->lock);
@@ -7288,8 +7290,6 @@ int stmmac_resume(struct device *dev)
 	mutex_unlock(&priv->lock);
 	rtnl_unlock();
 
-	phylink_mac_change(priv->phylink, true);
-
 	netif_device_attach(ndev);
 
 	return 0;
-- 
2.17.1

Re: [PATCH net 0/2] net: stmmac: fix WoL issue

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (refs/heads/master):

On Tue,  7 Sep 2021 18:56:45 +0800 you wrote:
> This patch set fixes stmmac not working after system resume back with WoL
> active. Thanks a lot for Russell King keeps looking into this issue.
> 
> Joakim Zhang (1):
>   net: stmmac: fix MAC not working when system resume back with WoL
>     active
> 
> [...]

Here is the summary with links:
  - [net,1/2] net: phylink: add suspend/resume support
    https://git.kernel.org/netdev/net/c/f97493657c63
  - [net,2/2] net: stmmac: fix MAC not working when system resume back with WoL active
    https://git.kernel.org/netdev/net/c/90702dcd19c0

You are awesome, thank you!
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