[PATCH v3 1/2] can: peak_usb: upgrades the handling of bus state changes

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This patch updates old code by using the functions published since by the
socket-can module. In particular, this new code better manages the change
of bus state by also using the value of the error counters that the driver
now systematically asks for when initializing the channel.

Signed-off-by: Stephane Grosjean <s.grosjean@xxxxxxxxxxxxxxx>
---
v2:
 - do the statistics and state update, even if the allocation of the skb
   fails.
v3:
 - do call can_change_state() even when cf is NULL
 - do supply Tx/Rx error counters in controller error skb
---
 drivers/net/can/usb/peak_usb/pcan_usb.c | 161 ++++++------------------
 1 file changed, 40 insertions(+), 121 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 1d6f77252f01..3af3136645ac 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -445,145 +445,64 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
 {
 	struct sk_buff *skb;
 	struct can_frame *cf;
-	enum can_state new_state;
+	enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
 
 	/* ignore this error until 1st ts received */
 	if (n == PCAN_USB_ERROR_QOVR)
 		if (!mc->pdev->time_ref.tick_count)
 			return 0;
 
-	new_state = mc->pdev->dev.can.state;
-
-	switch (mc->pdev->dev.can.state) {
-	case CAN_STATE_ERROR_ACTIVE:
-		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		fallthrough;
-
-	case CAN_STATE_ERROR_WARNING:
-		if (n & PCAN_USB_ERROR_BUS_HEAVY) {
-			new_state = CAN_STATE_ERROR_PASSIVE;
-			break;
-		}
-		if (n & PCAN_USB_ERROR_BUS_OFF) {
-			new_state = CAN_STATE_BUS_OFF;
-			break;
-		}
-		if (n & ~PCAN_USB_ERROR_BUS) {
-			/*
-			 * trick to bypass next comparison and process other
-			 * errors
-			 */
-			new_state = CAN_STATE_MAX;
-			break;
-		}
-		if ((n & PCAN_USB_ERROR_BUS_LIGHT) == 0) {
-			/* no error (back to active state) */
-			new_state = CAN_STATE_ERROR_ACTIVE;
-			break;
-		}
-		break;
-
-	case CAN_STATE_ERROR_PASSIVE:
-		if (n & PCAN_USB_ERROR_BUS_OFF) {
-			new_state = CAN_STATE_BUS_OFF;
-			break;
-		}
-		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		if (n & ~PCAN_USB_ERROR_BUS) {
-			/*
-			 * trick to bypass next comparison and process other
-			 * errors
-			 */
-			new_state = CAN_STATE_MAX;
-			break;
-		}
-
-		if ((n & PCAN_USB_ERROR_BUS_HEAVY) == 0) {
-			/* no error (back to warning state) */
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		break;
-
-	default:
-		/* do nothing waiting for restart */
-		return 0;
-	}
-
-	/* donot post any error if current state didn't change */
-	if (mc->pdev->dev.can.state == new_state)
-		return 0;
-
 	/* allocate an skb to store the error frame */
 	skb = alloc_can_err_skb(mc->netdev, &cf);
-	if (!skb)
-		return -ENOMEM;
 
-	switch (new_state) {
-	case CAN_STATE_BUS_OFF:
-		cf->can_id |= CAN_ERR_BUSOFF;
-		mc->pdev->dev.can.can_stats.bus_off++;
-		can_bus_off(mc->netdev);
-		break;
-
-	case CAN_STATE_ERROR_PASSIVE:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
-				CAN_ERR_CRTL_TX_PASSIVE :
-				CAN_ERR_CRTL_RX_PASSIVE;
-		cf->data[6] = mc->pdev->bec.txerr;
-		cf->data[7] = mc->pdev->bec.rxerr;
-
-		mc->pdev->dev.can.can_stats.error_passive++;
-		break;
+	if (n & PCAN_USB_ERROR_RXQOVR) {
+		/* data overrun interrupt */
+		netdev_dbg(mc->netdev, "data overrun interrupt\n");
+		mc->netdev->stats.rx_over_errors++;
+		mc->netdev->stats.rx_errors++;
+		if (cf) {
+			cf->can_id |= CAN_ERR_CRTL;
+			cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
+		}
+	}
 
-	case CAN_STATE_ERROR_WARNING:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
-				CAN_ERR_CRTL_TX_WARNING :
-				CAN_ERR_CRTL_RX_WARNING;
-		cf->data[6] = mc->pdev->bec.txerr;
-		cf->data[7] = mc->pdev->bec.rxerr;
+	if (n & PCAN_USB_ERROR_TXQFULL)
+		netdev_dbg(mc->netdev, "device Tx queue full)\n");
 
-		mc->pdev->dev.can.can_stats.error_warning++;
-		break;
+	if (n & PCAN_USB_ERROR_BUS_OFF) {
+		new_state = CAN_STATE_BUS_OFF;
+	} else if (n & PCAN_USB_ERROR_BUS_HEAVY) {
+		new_state = ((mc->pdev->bec.txerr >= 128) ||
+			     (mc->pdev->bec.rxerr >= 128)) ?
+				CAN_STATE_ERROR_PASSIVE :
+				CAN_STATE_ERROR_WARNING;
+	} else {
+		new_state = CAN_STATE_ERROR_ACTIVE;
+	}
 
-	case CAN_STATE_ERROR_ACTIVE:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = CAN_ERR_CRTL_ACTIVE;
+	/* handle change of state */
+	if (new_state != mc->pdev->dev.can.state) {
+		enum can_state tx_state =
+			(mc->pdev->bec.txerr >= mc->pdev->bec.rxerr) ?
+				new_state : 0;
+		enum can_state rx_state =
+			(mc->pdev->bec.txerr <= mc->pdev->bec.rxerr) ?
+				new_state : 0;
 
-		/* sync local copies of rxerr/txerr counters */
-		mc->pdev->bec.txerr = 0;
-		mc->pdev->bec.rxerr = 0;
-		break;
+		can_change_state(mc->netdev, cf, tx_state, rx_state);
 
-	default:
-		/* CAN_STATE_MAX (trick to handle other errors) */
-		if (n & PCAN_USB_ERROR_TXQFULL)
-			netdev_dbg(mc->netdev, "device Tx queue full)\n");
+		if (new_state == CAN_STATE_BUS_OFF) {
+			can_bus_off(mc->netdev);
 
-		if (n & PCAN_USB_ERROR_RXQOVR) {
-			netdev_dbg(mc->netdev, "data overrun interrupt\n");
-			cf->can_id |= CAN_ERR_CRTL;
-			cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
-			mc->netdev->stats.rx_over_errors++;
-			mc->netdev->stats.rx_errors++;
+		/* supply tx/rx error counters in case of controller error */
+		} else if (cf && (cf->can_id & CAN_ERR_CRTL)) {
+			cf->data[6] = mc->pdev->bec.txerr;
+			cf->data[7] = mc->pdev->bec.rxerr;
 		}
-
-		cf->data[6] = mc->pdev->bec.txerr;
-		cf->data[7] = mc->pdev->bec.rxerr;
-
-		new_state = mc->pdev->dev.can.state;
-		break;
 	}
 
-	mc->pdev->dev.can.state = new_state;
+	if (!skb)
+		return -ENOMEM;
 
 	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
 		struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
-- 
2.25.1




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