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") Reviewed-by: Markus Schneider-Pargmann Link: https://patch.msgid.link/20250929-m_can-fix-state-handling-v4-2-682b49b49d9a@pengutronix.de Signed-off-by: Marc Kleine-Budde --- 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 e1d725979685..ac864183a536 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