linux-kernel - [PATCH can-next v2 2/2] can: sja1000: sja1000_err(): use error counter for error state

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Message-Id: <20260123-sja1000-state-handling-v2-2-687498087dad@pengutronix.de>
Date: Fri, 23 Jan 2026 11:16:27 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Vincent Mailhol <mailhol@...nel.org>, 
 Michael Tretter <m.tretter@...gutronix.de>
Cc: Achim Baumgartner <abaumgartner@...con.com>, linux-can@...r.kernel.org, 
 linux-kernel@...r.kernel.org, kernel@...gutronix.de, 
 Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH can-next v2 2/2] can: sja1000: sja1000_err(): use error
 counter for error state

From: Michael Tretter <m.tretter@...gutronix.de>

The CAN controller sends the EPI interrupt whenever it reaches the error
passive status or enters the error active status from the error passive
status.

Instead of keeping track of the controller status in the driver, read the
txerr and rxerr counters and use can_state_get_by_berr_counter() to
determine the state of the CAN controller.

Suggested-by: Achim Baumgartner <abaumgartner@...con.com>
Signed-off-by: Michael Tretter <m.tretter@...gutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/sja1000/sja1000.c | 33 +++++++--------------------------
 1 file changed, 7 insertions(+), 26 deletions(-)

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index ae3244b63b65..67fccc15ed20 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -407,10 +407,9 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 {
 	struct sja1000_priv *priv = netdev_priv(dev);
 	struct net_device_stats *stats = &dev->stats;
+	enum can_state state, rx_state, tx_state;
 	struct can_frame *cf;
 	struct sk_buff *skb;
-	enum can_state state = priv->can.state;
-	enum can_state rx_state, tx_state;
 	struct can_berr_counter bec;
 	uint8_t ecc, alc;
 	int ret = 0;
@@ -418,6 +417,12 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 	skb = alloc_can_err_skb(dev, &cf);
 
 	sja1000_get_berr_counter(dev, &bec);
+	can_state_get_by_berr_counter(dev, &bec, &tx_state, &rx_state);
+
+	if (status & SR_BS)
+		rx_state = CAN_STATE_BUS_OFF;
+
+	state = max(tx_state, rx_state);
 
 	if (isrc & IRQ_DOI) {
 		/* data overrun interrupt */
@@ -440,18 +445,6 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 		if (priv->flags & SJA1000_QUIRK_RESET_ON_OVERRUN)
 			ret = IRQ_WAKE_THREAD;
 	}
-
-	if (isrc & IRQ_EI) {
-		/* error warning interrupt */
-		netdev_dbg(dev, "error warning interrupt\n");
-
-		if (status & SR_BS)
-			state = CAN_STATE_BUS_OFF;
-		else if (status & SR_ES)
-			state = CAN_STATE_ERROR_WARNING;
-		else
-			state = CAN_STATE_ERROR_ACTIVE;
-	}
 	if (state != CAN_STATE_BUS_OFF && skb) {
 		cf->can_id |= CAN_ERR_CNT;
 		cf->data[6] = bec.txerr;
@@ -493,15 +486,6 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 			stats->rx_errors++;
 		}
 	}
-	if (isrc & IRQ_EPI) {
-		/* error passive interrupt */
-		netdev_dbg(dev, "error passive interrupt\n");
-
-		if (state == CAN_STATE_ERROR_PASSIVE)
-			state = CAN_STATE_ERROR_WARNING;
-		else
-			state = CAN_STATE_ERROR_PASSIVE;
-	}
 	if (isrc & IRQ_ALI) {
 		/* arbitration lost interrupt */
 		netdev_dbg(dev, "arbitration lost interrupt\n");
@@ -514,9 +498,6 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 	}
 
 	if (state != priv->can.state) {
-		tx_state = bec.txerr >= bec.rxerr ? state : 0;
-		rx_state = bec.txerr <= bec.rxerr ? state : 0;
-
 		can_change_state(dev, cf, tx_state, rx_state);
 
 		if(state == CAN_STATE_BUS_OFF)

-- 
2.51.0