[v2] can: m_can: fix pm_runtime and CAN state handling

[PATCH v2 3/7] can: m_can: m_can_handle_state_errors(): fix CAN state transition to Error Active

Posted by Marc Kleine-Budde 3 weeks, 2 days ago

The CAN Error State is determined by the receive and transmit error
counters. The CAN error counters decrease when reception/transmission
is successful, so that a status transition back to the Error Active
status is possible. This transition is not handled by
m_can_handle_state_errors().

Add the missing detection of the Error Active state to
m_can_handle_state_errors() and extend the handling of this state in
m_can_handle_state_change().

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Fixes: cd0d83eab2e0 ("can: m_can: m_can_handle_state_change(): fix state change")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/m_can.c | 55 ++++++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 22 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 16b38e6c3985..3edf01b098a4 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -812,6 +812,9 @@ static int m_can_handle_state_change(struct net_device *dev,
 	u32 timestamp = 0;
 
 	switch (new_state) {
+	case CAN_STATE_ERROR_ACTIVE:
+		cdev->can.state = CAN_STATE_ERROR_ACTIVE;
+		break;
 	case CAN_STATE_ERROR_WARNING:
 		/* error warning state */
 		cdev->can.can_stats.error_warning++;
@@ -841,6 +844,12 @@ static int m_can_handle_state_change(struct net_device *dev,
 	__m_can_get_berr_counter(dev, &bec);
 
 	switch (new_state) {
+	case CAN_STATE_ERROR_ACTIVE:
+		cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
+		cf->data[1] = CAN_ERR_CRTL_ACTIVE;
+		cf->data[6] = bec.txerr;
+		cf->data[7] = bec.rxerr;
+		break;
 	case CAN_STATE_ERROR_WARNING:
 		/* error warning state */
 		cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
@@ -877,30 +886,33 @@ static int m_can_handle_state_change(struct net_device *dev,
 	return 1;
 }
 
-static int m_can_handle_state_errors(struct net_device *dev, u32 psr)
+static enum can_state
+m_can_state_get_by_psr(struct m_can_classdev *cdev)
+{
+	u32 reg_psr;
+
+	reg_psr = m_can_read(cdev, M_CAN_PSR);
+
+	if (reg_psr & PSR_BO)
+		return CAN_STATE_BUS_OFF;
+	if (reg_psr & PSR_EP)
+		return CAN_STATE_ERROR_PASSIVE;
+	if (reg_psr & PSR_EW)
+		return CAN_STATE_ERROR_WARNING;
+
+	return CAN_STATE_ERROR_ACTIVE;
+}
+
+static int m_can_handle_state_errors(struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
-	int work_done = 0;
+	enum can_state new_state;
 
-	if (psr & PSR_EW && cdev->can.state != CAN_STATE_ERROR_WARNING) {
-		netdev_dbg(dev, "entered error warning state\n");
-		work_done += m_can_handle_state_change(dev,
-						       CAN_STATE_ERROR_WARNING);
-	}
+	new_state = m_can_state_get_by_psr(cdev);
+	if (new_state == cdev->can.state)
+		return 0;
 
-	if (psr & PSR_EP && cdev->can.state != CAN_STATE_ERROR_PASSIVE) {
-		netdev_dbg(dev, "entered error passive state\n");
-		work_done += m_can_handle_state_change(dev,
-						       CAN_STATE_ERROR_PASSIVE);
-	}
-
-	if (psr & PSR_BO && cdev->can.state != CAN_STATE_BUS_OFF) {
-		netdev_dbg(dev, "entered error bus off state\n");
-		work_done += m_can_handle_state_change(dev,
-						       CAN_STATE_BUS_OFF);
-	}
-
-	return work_done;
+	return m_can_handle_state_change(dev, new_state);
 }
 
 static void m_can_handle_other_err(struct net_device *dev, u32 irqstatus)
@@ -1031,8 +1043,7 @@ static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
 	}
 
 	if (irqstatus & IR_ERR_STATE)
-		work_done += m_can_handle_state_errors(dev,
-						       m_can_read(cdev, M_CAN_PSR));
+		work_done += m_can_handle_state_errors(dev);
 
 	if (irqstatus & IR_ERR_BUS_30X)
 		work_done += m_can_handle_bus_errors(dev, irqstatus,

-- 
2.51.0

Re: [PATCH v2 3/7] can: m_can: m_can_handle_state_errors(): fix CAN state transition to Error Active

Posted by Markus Schneider-Pargmann 3 weeks, 1 day ago

On Tue Sep 9, 2025 at 7:53 PM CEST, Marc Kleine-Budde wrote:
> The CAN Error State is determined by the receive and transmit error
> counters. The CAN error counters decrease when reception/transmission
> is successful, so that a status transition back to the Error Active
> status is possible. This transition is not handled by
> m_can_handle_state_errors().
>
> Add the missing detection of the Error Active state to
> m_can_handle_state_errors() and extend the handling of this state in
> m_can_handle_state_change().
>
> Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
> Fixes: cd0d83eab2e0 ("can: m_can: m_can_handle_state_change(): fix state change")
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

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

> ---
>  drivers/net/can/m_can/m_can.c | 55 ++++++++++++++++++++++++++-----------------
>  1 file changed, 33 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 16b38e6c3985..3edf01b098a4 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -812,6 +812,9 @@ static int m_can_handle_state_change(struct net_device *dev,
>  	u32 timestamp = 0;
>  
>  	switch (new_state) {
> +	case CAN_STATE_ERROR_ACTIVE:
> +		cdev->can.state = CAN_STATE_ERROR_ACTIVE;
> +		break;
>  	case CAN_STATE_ERROR_WARNING:
>  		/* error warning state */
>  		cdev->can.can_stats.error_warning++;
> @@ -841,6 +844,12 @@ static int m_can_handle_state_change(struct net_device *dev,
>  	__m_can_get_berr_counter(dev, &bec);
>  
>  	switch (new_state) {
> +	case CAN_STATE_ERROR_ACTIVE:
> +		cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
> +		cf->data[1] = CAN_ERR_CRTL_ACTIVE;
> +		cf->data[6] = bec.txerr;
> +		cf->data[7] = bec.rxerr;
> +		break;
>  	case CAN_STATE_ERROR_WARNING:
>  		/* error warning state */
>  		cf->can_id |= CAN_ERR_CRTL | CAN_ERR_CNT;
> @@ -877,30 +886,33 @@ static int m_can_handle_state_change(struct net_device *dev,
>  	return 1;
>  }
>  
> -static int m_can_handle_state_errors(struct net_device *dev, u32 psr)
> +static enum can_state
> +m_can_state_get_by_psr(struct m_can_classdev *cdev)
> +{
> +	u32 reg_psr;
> +
> +	reg_psr = m_can_read(cdev, M_CAN_PSR);
> +
> +	if (reg_psr & PSR_BO)
> +		return CAN_STATE_BUS_OFF;
> +	if (reg_psr & PSR_EP)
> +		return CAN_STATE_ERROR_PASSIVE;
> +	if (reg_psr & PSR_EW)
> +		return CAN_STATE_ERROR_WARNING;
> +
> +	return CAN_STATE_ERROR_ACTIVE;
> +}
> +
> +static int m_can_handle_state_errors(struct net_device *dev)
>  {
>  	struct m_can_classdev *cdev = netdev_priv(dev);
> -	int work_done = 0;
> +	enum can_state new_state;
>  
> -	if (psr & PSR_EW && cdev->can.state != CAN_STATE_ERROR_WARNING) {
> -		netdev_dbg(dev, "entered error warning state\n");
> -		work_done += m_can_handle_state_change(dev,
> -						       CAN_STATE_ERROR_WARNING);
> -	}
> +	new_state = m_can_state_get_by_psr(cdev);
> +	if (new_state == cdev->can.state)
> +		return 0;
>  
> -	if (psr & PSR_EP && cdev->can.state != CAN_STATE_ERROR_PASSIVE) {
> -		netdev_dbg(dev, "entered error passive state\n");
> -		work_done += m_can_handle_state_change(dev,
> -						       CAN_STATE_ERROR_PASSIVE);
> -	}
> -
> -	if (psr & PSR_BO && cdev->can.state != CAN_STATE_BUS_OFF) {
> -		netdev_dbg(dev, "entered error bus off state\n");
> -		work_done += m_can_handle_state_change(dev,
> -						       CAN_STATE_BUS_OFF);
> -	}
> -
> -	return work_done;
> +	return m_can_handle_state_change(dev, new_state);
>  }
>  
>  static void m_can_handle_other_err(struct net_device *dev, u32 irqstatus)
> @@ -1031,8 +1043,7 @@ static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
>  	}
>  
>  	if (irqstatus & IR_ERR_STATE)
> -		work_done += m_can_handle_state_errors(dev,
> -						       m_can_read(cdev, M_CAN_PSR));
> +		work_done += m_can_handle_state_errors(dev);
>  
>  	if (irqstatus & IR_ERR_BUS_30X)
>  		work_done += m_can_handle_bus_errors(dev, irqstatus,

[PATCH v2 1/7] can: m_can: m_can_plat_remove(): add missing pm_runtime_disable()
[PATCH v2 2/7] can: m_can: only handle active interrupts
[PATCH v2 3/7] can: m_can: m_can_handle_state_errors(): fix CAN state transition to Error Active
[PATCH v2 4/7] can: m_can: m_can_chip_config(): bring up interface in correct state
[PATCH v2 5/7] can: m_can: fix CAN state in system PM
[PATCH v2 6/7] can: m_can: m_can_get_berr_counter(): don't wake up controller if interface is down
[PATCH v2 7/7] can: m_can: add optional support for reset