Merge patch series "can: m_can: Fix polling and other issues"

Markus Schneider-Pargmann <msp@baylibre.com> says:

these are a number of fixes for m_can that fix polling mode and some
other issues that I saw while working on the code.

Changes in v2
-------------
 - Fixed one multiline comment
 - Rebased to v6.11-rc1

Previous versions
-----------------
 v1: https://lore.kernel.org/lkml/20240726195944.2414812-1-msp@baylibre.com/

Link: https://lore.kernel.org/all/20240805183047.305630-1-msp@baylibre.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: marckleinebudde

drivers/net/can/m_can/m_can.c

@@ -483,11 +483,10 @@ static inline void m_can_disable_all_interrupts(struct m_can_classdev *cdev)
 {
 	m_can_coalescing_disable(cdev);
 	m_can_write(cdev, M_CAN_ILE, 0x0);
-	cdev->active_interrupts = 0x0;
 
 	if (!cdev->net->irq) {
 		dev_dbg(cdev->dev, "Stop hrtimer\n");
-		hrtimer_cancel(&cdev->hrtimer);
+		hrtimer_try_to_cancel(&cdev->hrtimer);
 	}
 }
 
@@ -1037,22 +1036,6 @@ static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
 	return work_done;
 }
 
-static int m_can_rx_peripheral(struct net_device *dev, u32 irqstatus)
-{
-	struct m_can_classdev *cdev = netdev_priv(dev);
-	int work_done;
-
-	work_done = m_can_rx_handler(dev, NAPI_POLL_WEIGHT, irqstatus);
-
-	/* Don't re-enable interrupts if the driver had a fatal error
-	 * (e.g., FIFO read failure).
-	 */
-	if (work_done < 0)
-		m_can_disable_all_interrupts(cdev);
-
-	return work_done;
-}
-
 static int m_can_poll(struct napi_struct *napi, int quota)
 {
 	struct net_device *dev = napi->dev;
@@ -1217,16 +1200,18 @@ static void m_can_coalescing_update(struct m_can_classdev *cdev, u32 ir)
 			      HRTIMER_MODE_REL);
 }
 
-static irqreturn_t m_can_isr(int irq, void *dev_id)
+/* This interrupt handler is called either from the interrupt thread or a
+ * hrtimer. This has implications like cancelling a timer won't be possible
+ * blocking.
+ */
+static int m_can_interrupt_handler(struct m_can_classdev *cdev)
 {
-	struct net_device *dev = (struct net_device *)dev_id;
-	struct m_can_classdev *cdev = netdev_priv(dev);
+	struct net_device *dev = cdev->net;
 	u32 ir;
+	int ret;
 
-	if (pm_runtime_suspended(cdev->dev)) {
-		m_can_coalescing_disable(cdev);
+	if (pm_runtime_suspended(cdev->dev))
 		return IRQ_NONE;
-	}
 
 	ir = m_can_read(cdev, M_CAN_IR);
 	m_can_coalescing_update(cdev, ir);
@@ -1250,11 +1235,9 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 			m_can_disable_all_interrupts(cdev);
 			napi_schedule(&cdev->napi);
 		} else {
-			int pkts;
-
-			pkts = m_can_rx_peripheral(dev, ir);
-			if (pkts < 0)
-				goto out_fail;
+			ret = m_can_rx_handler(dev, NAPI_POLL_WEIGHT, ir);
+			if (ret < 0)
+				return ret;
 		}
 	}
 
@@ -1272,25 +1255,41 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 	} else  {
 		if (ir & (IR_TEFN | IR_TEFW)) {
 			/* New TX FIFO Element arrived */
-			if (m_can_echo_tx_event(dev) != 0)
-				goto out_fail;
+			ret = m_can_echo_tx_event(dev);
+			if (ret != 0)
+				return ret;
 		}
 	}
 
 	if (cdev->is_peripheral)
 		can_rx_offload_threaded_irq_finish(&cdev->offload);
 
 	return IRQ_HANDLED;
+}
 
-out_fail:
-	m_can_disable_all_interrupts(cdev);
-	return IRQ_HANDLED;
+static irqreturn_t m_can_isr(int irq, void *dev_id)
+{
+	struct net_device *dev = (struct net_device *)dev_id;
+	struct m_can_classdev *cdev = netdev_priv(dev);
+	int ret;
+
+	ret =  m_can_interrupt_handler(cdev);
+	if (ret < 0) {
+		m_can_disable_all_interrupts(cdev);
+		return IRQ_HANDLED;
+	}
+
+	return ret;
 }
 
 static enum hrtimer_restart m_can_coalescing_timer(struct hrtimer *timer)
 {
 	struct m_can_classdev *cdev = container_of(timer, struct m_can_classdev, hrtimer);
 
+	if (cdev->can.state == CAN_STATE_BUS_OFF ||
+	    cdev->can.state == CAN_STATE_STOPPED)
+		return HRTIMER_NORESTART;
+
 	irq_wake_thread(cdev->net->irq, cdev->net);
 
 	return HRTIMER_NORESTART;
@@ -1542,6 +1541,7 @@ static int m_can_chip_config(struct net_device *dev)
 		else
 			interrupts &= ~(IR_ERR_LEC_31X);
 	}
+	cdev->active_interrupts = 0;
 	m_can_interrupt_enable(cdev, interrupts);
 
 	/* route all interrupts to INT0 */
@@ -1991,8 +1991,17 @@ static enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)
 {
 	struct m_can_classdev *cdev = container_of(timer, struct
 						   m_can_classdev, hrtimer);
+	int ret;
 
-	m_can_isr(0, cdev->net);
+	if (cdev->can.state == CAN_STATE_BUS_OFF ||
+	    cdev->can.state == CAN_STATE_STOPPED)
+		return HRTIMER_NORESTART;
+
+	ret = m_can_interrupt_handler(cdev);
+
+	/* On error or if napi is scheduled to read, stop the timer */
+	if (ret < 0 || napi_is_scheduled(&cdev->napi))
+		return HRTIMER_NORESTART;
 
 	hrtimer_forward_now(timer, ms_to_ktime(HRTIMER_POLL_INTERVAL_MS));
 
@@ -2175,7 +2184,7 @@ static int m_can_set_coalesce(struct net_device *dev,
 	return 0;
 }
 
-static const struct ethtool_ops m_can_ethtool_ops = {
+static const struct ethtool_ops m_can_ethtool_ops_coalescing = {
 	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS_IRQ |
 		ETHTOOL_COALESCE_RX_MAX_FRAMES_IRQ |
 		ETHTOOL_COALESCE_TX_USECS_IRQ |
@@ -2186,18 +2195,20 @@ static const struct ethtool_ops m_can_ethtool_ops = {
 	.set_coalesce = m_can_set_coalesce,
 };
 
-static const struct ethtool_ops m_can_ethtool_ops_polling = {
+static const struct ethtool_ops m_can_ethtool_ops = {
 	.get_ts_info = ethtool_op_get_ts_info,
 };
 
-static int register_m_can_dev(struct net_device *dev)
+static int register_m_can_dev(struct m_can_classdev *cdev)
 {
+	struct net_device *dev = cdev->net;
+
 	dev->flags |= IFF_ECHO;	/* we support local echo */
 	dev->netdev_ops = &m_can_netdev_ops;
-	if (dev->irq)
-		dev->ethtool_ops = &m_can_ethtool_ops;
+	if (dev->irq && cdev->is_peripheral)
+		dev->ethtool_ops = &m_can_ethtool_ops_coalescing;
 	else
-		dev->ethtool_ops = &m_can_ethtool_ops_polling;
+		dev->ethtool_ops = &m_can_ethtool_ops;
 
 	return register_candev(dev);
 }
@@ -2383,7 +2394,7 @@ int m_can_class_register(struct m_can_classdev *cdev)
 	if (ret)
 		goto rx_offload_del;
 
-	ret = register_m_can_dev(cdev->net);
+	ret = register_m_can_dev(cdev);
 	if (ret) {
 		dev_err(cdev->dev, "registering %s failed (err=%d)\n",
 			cdev->net->name, ret);
@@ -2430,12 +2441,15 @@ int m_can_class_suspend(struct device *dev)
 		netif_device_detach(ndev);
 
 		/* leave the chip running with rx interrupt enabled if it is
-		 * used as a wake-up source.
+		 * used as a wake-up source. Coalescing needs to be reset then,
+		 * the timer is cancelled here, interrupts are done in resume.
 		 */
-		if (cdev->pm_wake_source)
+		if (cdev->pm_wake_source) {
+			hrtimer_cancel(&cdev->hrtimer);
 			m_can_write(cdev, M_CAN_IE, IR_RF0N);
-		else
+		} else {
 			m_can_stop(ndev);
+		}
 
 		m_can_clk_stop(cdev);
 	}
@@ -2465,6 +2479,13 @@ int m_can_class_resume(struct device *dev)
 			return ret;
 
 		if (cdev->pm_wake_source) {
+			/* Restore active interrupts but disable coalescing as
+			 * we may have missed important waterlevel interrupts
+			 * between suspend and resume. Timers are already
+			 * stopped in suspend. Here we enable all interrupts
+			 * again.
+			 */
+			cdev->active_interrupts |= IR_RF0N | IR_TEFN;
 			m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
 		} else {
 			ret  = m_can_start(ndev);