3 files changed, 61 insertions, 124 deletions

diff --git a/drivers/net/ipa/ipa_modem.c b/drivers/net/ipa/ipa_modem.c
index 423422a2a445..1d1be92fbebc 100644
--- a/drivers/net/ipa/ipa_modem.c
+++ b/drivers/net/ipa/ipa_modem.c
@@ -39,10 +39,14 @@ enum ipa_modem_state {
 /**
  * struct ipa_priv - IPA network device private data
  * @ipa:	IPA pointer
+ * @tx:		Transmit endpoint pointer
+ * @rx:		Receive endpoint pointer
  * @work:	Work structure used to wake the modem netdev TX queue
  */
 struct ipa_priv {
 	struct ipa *ipa;
+	struct ipa_endpoint *tx;
+	struct ipa_endpoint *rx;
 	struct work_struct work;
 };
 
@@ -59,11 +63,11 @@ static int ipa_open(struct net_device *netdev)
 	if (ret < 0)
 		goto err_power_put;
 
-	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	ret = ipa_endpoint_enable_one(priv->tx);
 	if (ret)
 		goto err_power_put;
 
-	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+	ret = ipa_endpoint_enable_one(priv->rx);
 	if (ret)
 		goto err_disable_tx;
 
@@ -75,7 +79,7 @@ static int ipa_open(struct net_device *netdev)
 	return 0;
 
 err_disable_tx:
-	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	ipa_endpoint_disable_one(priv->tx);
 err_power_put:
 	pm_runtime_put_noidle(dev);
 
@@ -97,8 +101,8 @@ static int ipa_stop(struct net_device *netdev)
 
 	netif_stop_queue(netdev);
 
-	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
-	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	ipa_endpoint_disable_one(priv->rx);
+	ipa_endpoint_disable_one(priv->tx);
 out_power_put:
 	pm_runtime_mark_last_busy(dev);
 	(void)pm_runtime_put_autosuspend(dev);
@@ -106,13 +110,16 @@ out_power_put:
 	return 0;
 }
 
-/** ipa_start_xmit() - Transmits an skb.
- * @skb: skb to be transmitted
- * @dev: network device
+/** ipa_start_xmit() - Transmit an skb
+ * @skb:	Socket buffer to be transmitted
+ * @netdev:	Network device
  *
- * Return codes:
- * NETDEV_TX_OK: Success
- * NETDEV_TX_BUSY: Error while transmitting the skb. Try again later
+ * Return: NETDEV_TX_OK if successful (or dropped), NETDEV_TX_BUSY otherwise
+
+ * Normally NETDEV_TX_OK indicates the buffer was successfully transmitted.
+ * If the buffer has an unexpected protocol or its size is out of range it
+ * is quietly dropped, returning NETDEV_TX_OK.  NETDEV_TX_BUSY indicates
+ * the buffer cannot be sent at this time and should retried later.
  */
 static netdev_tx_t
 ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev)
@@ -132,29 +139,41 @@ ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev)
 	if (endpoint->config.qmap && skb->protocol != htons(ETH_P_MAP))
 		goto err_drop_skb;
 
-	/* The hardware must be powered for us to transmit */
+	/* The hardware must be powered for us to transmit, so if we're not
+	 * ready we want the network stack to stop queueing until power is
+	 * ACTIVE.  Once runtime resume has completed, we inform the network
+	 * stack it's OK to try transmitting again.
+	 *
+	 * We learn from pm_runtime_get() whether the hardware is powered.
+	 * If it was not, powering up is either started or already underway.
+	 * And in that case we want to disable queueing, expecting it to be
+	 * re-enabled once power is ACTIVE.  But runtime PM and network
+	 * transmit run concurrently, and if we're not careful the requests
+	 * to stop and start queueing could occur in the wrong order.
+	 *
+	 * For that reason we *always* stop queueing here, *before* the call
+	 * to pm_runtime_get().  If we determine here that power is ACTIVE,
+	 * we restart queueing before transmitting the SKB.  Otherwise
+	 * queueing will eventually be enabled after resume completes.
+	 */
+	netif_stop_queue(netdev);
+
 	dev = &ipa->pdev->dev;
 	ret = pm_runtime_get(dev);
 	if (ret < 1) {
 		/* If a resume won't happen, just drop the packet */
 		if (ret < 0 && ret != -EINPROGRESS) {
-			ipa_power_modem_queue_active(ipa);
+			netif_wake_queue(netdev);
 			pm_runtime_put_noidle(dev);
 			goto err_drop_skb;
 		}
 
-		/* No power (yet).  Stop the network stack from transmitting
-		 * until we're resumed; ipa_modem_resume() arranges for the
-		 * TX queue to be started again.
-		 */
-		ipa_power_modem_queue_stop(ipa);
-
 		pm_runtime_put_noidle(dev);
 
 		return NETDEV_TX_BUSY;
 	}
 
-	ipa_power_modem_queue_active(ipa);
+	netif_wake_queue(netdev);
 
 	ret = ipa_endpoint_skb_tx(endpoint, skb);
 
@@ -233,14 +252,14 @@ static void ipa_modem_netdev_setup(struct net_device *netdev)
  */
 void ipa_modem_suspend(struct net_device *netdev)
 {
-	struct ipa_priv *priv = netdev_priv(netdev);
-	struct ipa *ipa = priv->ipa;
+	struct ipa_priv *priv;
 
 	if (!(netdev->flags & IFF_UP))
 		return;
 
-	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
-	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
+	priv = netdev_priv(netdev);
+	ipa_endpoint_suspend_one(priv->rx);
+	ipa_endpoint_suspend_one(priv->tx);
 }
 
 /**
@@ -258,7 +277,7 @@ static void ipa_modem_wake_queue_work(struct work_struct *work)
 {
 	struct ipa_priv *priv = container_of(work, struct ipa_priv, work);
 
-	ipa_power_modem_queue_wake(priv->ipa);
+	netif_wake_queue(priv->tx->netdev);
 }
 
 /** ipa_modem_resume() - resume callback for runtime_pm
@@ -268,14 +287,14 @@ static void ipa_modem_wake_queue_work(struct work_struct *work)
  */
 void ipa_modem_resume(struct net_device *netdev)
 {
-	struct ipa_priv *priv = netdev_priv(netdev);
-	struct ipa *ipa = priv->ipa;
+	struct ipa_priv *priv;
 
 	if (!(netdev->flags & IFF_UP))
 		return;
 
-	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
-	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
+	priv = netdev_priv(netdev);
+	ipa_endpoint_resume_one(priv->tx);
+	ipa_endpoint_resume_one(priv->rx);
 
 	/* Arrange for the TX queue to be restarted */
 	(void)queue_pm_work(&priv->work);
@@ -306,16 +325,21 @@ int ipa_modem_start(struct ipa *ipa)
 	SET_NETDEV_DEV(netdev, &ipa->pdev->dev);
 	priv = netdev_priv(netdev);
 	priv->ipa = ipa;
+	priv->tx = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
+	priv->rx = ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX];
 	INIT_WORK(&priv->work, ipa_modem_wake_queue_work);
-	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = netdev;
-	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = netdev;
+
+	priv->tx->netdev = netdev;
+	priv->rx->netdev = netdev;
+
 	ipa->modem_netdev = netdev;
 
 	ret = register_netdev(netdev);
 	if (ret) {
 		ipa->modem_netdev = NULL;
-		ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
-		ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
+		priv->rx->netdev = NULL;
+		priv->tx->netdev = NULL;
+
 		free_netdev(netdev);
 	}
 
@@ -355,9 +379,11 @@ int ipa_modem_stop(struct ipa *ipa)
 		if (netdev->flags & IFF_UP)
 			(void)ipa_stop(netdev);
 		unregister_netdev(netdev);
+
 		ipa->modem_netdev = NULL;
-		ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
-		ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
+		priv->rx->netdev = NULL;
+		priv->tx->netdev = NULL;
+
 		free_netdev(netdev);
 	}
 
diff --git a/drivers/net/ipa/ipa_power.c b/drivers/net/ipa/ipa_power.c
index e223886123ce..128a816f6523 100644
--- a/drivers/net/ipa/ipa_power.c
+++ b/drivers/net/ipa/ipa_power.c
@@ -38,15 +38,11 @@
  * enum ipa_power_flag - IPA power flags
  * @IPA_POWER_FLAG_RESUMED:	Whether resume from suspend has been signaled
  * @IPA_POWER_FLAG_SYSTEM:	Hardware is system (not runtime) suspended
- * @IPA_POWER_FLAG_STOPPED:	Modem TX is disabled by ipa_start_xmit()
- * @IPA_POWER_FLAG_STARTED:	Modem TX was enabled by ipa_runtime_resume()
  * @IPA_POWER_FLAG_COUNT:	Number of defined power flags
  */
 enum ipa_power_flag {
 	IPA_POWER_FLAG_RESUMED,
 	IPA_POWER_FLAG_SYSTEM,
-	IPA_POWER_FLAG_STOPPED,
-	IPA_POWER_FLAG_STARTED,
 	IPA_POWER_FLAG_COUNT,		/* Last; not a flag */
 };
 
@@ -55,7 +51,6 @@ enum ipa_power_flag {
  * @dev:		IPA device pointer
  * @core:		IPA core clock
  * @qmp:		QMP handle for AOSS communication
- * @spinlock:		Protects modem TX queue enable/disable
  * @flags:		Boolean state flags
  * @interconnect_count:	Number of elements in interconnect[]
  * @interconnect:	Interconnect array
@@ -64,7 +59,6 @@ struct ipa_power {
 	struct device *dev;
 	struct clk *core;
 	struct qmp *qmp;
-	spinlock_t spinlock;	/* used with STOPPED/STARTED power flags */
 	DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
 	u32 interconnect_count;
 	struct icc_bulk_data interconnect[] __counted_by(interconnect_count);
@@ -233,70 +227,6 @@ void ipa_power_suspend_handler(struct ipa *ipa, enum ipa_irq_id irq_id)
 	ipa_interrupt_suspend_clear_all(ipa->interrupt);
 }
 
-/* The next few functions coordinate stopping and starting the modem
- * network device transmit queue.
- *
- * Transmit can be running concurrent with power resume, and there's a
- * chance the resume completes before the transmit path stops the queue,
- * leaving the queue in a stopped state.  The next two functions are used
- * to avoid this: ipa_power_modem_queue_stop() is used by ipa_start_xmit()
- * to conditionally stop the TX queue; and ipa_power_modem_queue_start()
- * is used by ipa_runtime_resume() to conditionally restart it.
- *
- * Two flags and a spinlock are used.  If the queue is stopped, the STOPPED
- * power flag is set.  And if the queue is started, the STARTED flag is set.
- * The queue is only started on resume if the STOPPED flag is set.  And the
- * queue is only started in ipa_start_xmit() if the STARTED flag is *not*
- * set.  As a result, the queue remains operational if the two activites
- * happen concurrently regardless of the order they complete.  The spinlock
- * ensures the flag and TX queue operations are done atomically.
- *
- * The first function stops the modem netdev transmit queue, but only if
- * the STARTED flag is *not* set.  That flag is cleared if it was set.
- * If the queue is stopped, the STOPPED flag is set.  This is called only
- * from the power ->runtime_resume operation.
- */
-void ipa_power_modem_queue_stop(struct ipa *ipa)
-{
-	struct ipa_power *power = ipa->power;
-	unsigned long flags;
-
-	spin_lock_irqsave(&power->spinlock, flags);
-
-	if (!__test_and_clear_bit(IPA_POWER_FLAG_STARTED, power->flags)) {
-		netif_stop_queue(ipa->modem_netdev);
-		__set_bit(IPA_POWER_FLAG_STOPPED, power->flags);
-	}
-
-	spin_unlock_irqrestore(&power->spinlock, flags);
-}
-
-/* This function starts the modem netdev transmit queue, but only if the
- * STOPPED flag is set.  That flag is cleared if it was set.  If the queue
- * was restarted, the STARTED flag is set; this allows ipa_start_xmit()
- * to skip stopping the queue in the event of a race.
- */
-void ipa_power_modem_queue_wake(struct ipa *ipa)
-{
-	struct ipa_power *power = ipa->power;
-	unsigned long flags;
-
-	spin_lock_irqsave(&power->spinlock, flags);
-
-	if (__test_and_clear_bit(IPA_POWER_FLAG_STOPPED, power->flags)) {
-		__set_bit(IPA_POWER_FLAG_STARTED, power->flags);
-		netif_wake_queue(ipa->modem_netdev);
-	}
-
-	spin_unlock_irqrestore(&power->spinlock, flags);
-}
-
-/* This function clears the STARTED flag once the TX queue is operating */
-void ipa_power_modem_queue_active(struct ipa *ipa)
-{
-	clear_bit(IPA_POWER_FLAG_STARTED, ipa->power->flags);
-}
-
 static int ipa_power_retention_init(struct ipa_power *power)
 {
 	struct qmp *qmp = qmp_get(power->dev);
@@ -385,7 +315,6 @@ ipa_power_init(struct device *dev, const struct ipa_power_data *data)
 	}
 	power->dev = dev;
 	power->core = clk;
-	spin_lock_init(&power->spinlock);
 	power->interconnect_count = data->interconnect_count;
 
 	ret = ipa_interconnect_init(power, data->interconnect_data);
diff --git a/drivers/net/ipa/ipa_power.h b/drivers/net/ipa/ipa_power.h
index 3a4c59ea1222..718aacf5e2b2 100644
--- a/drivers/net/ipa/ipa_power.h
+++ b/drivers/net/ipa/ipa_power.h
@@ -24,24 +24,6 @@ extern const struct dev_pm_ops ipa_pm_ops;
 u32 ipa_core_clock_rate(struct ipa *ipa);
 
 /**
- * ipa_power_modem_queue_stop() - Possibly stop the modem netdev TX queue
- * @ipa:	IPA pointer
- */
-void ipa_power_modem_queue_stop(struct ipa *ipa);
-
-/**
- * ipa_power_modem_queue_wake() - Possibly wake the modem netdev TX queue
- * @ipa:	IPA pointer
- */
-void ipa_power_modem_queue_wake(struct ipa *ipa);
-
-/**
- * ipa_power_modem_queue_active() - Report modem netdev TX queue active
- * @ipa:	IPA pointer
- */
-void ipa_power_modem_queue_active(struct ipa *ipa);
-
-/**
  * ipa_power_retention() - Control register retention on power collapse
  * @ipa:	IPA pointer
  * @enable:	Whether retention should be enabled or disabled