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From:   Frank Jungclaus <frank.jungclaus@esd.eu>
To:     linux-can@vger.kernel.org, Marc Kleine-Budde <mkl@pengutronix.de>,
        Wolfgang Grandegger <wg@grandegger.com>,
        Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc:     =?UTF-8?q?Stefan=20M=C3=A4tje?= <stefan.maetje@esd.eu>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Frank Jungclaus <frank.jungclaus@esd.eu>
Subject: [PATCH 5/6] can: esd_usb: Improved support for CAN_CTRLMODE_BERR_REPORTING
Date:   Fri,  8 Jul 2022 20:12:36 +0200
Message-Id: <20220708181235.4104943-6-frank.jungclaus@esd.eu>
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Bus error reporting has already been implemented for a long time, but
before it was always active! Now it's user controllable by means off the
"berr-reporting" parameter given to "ip link set ... ", which sets
CAN_CTRLMODE_BERR_REPORTING within priv->can.ctrlmode.

In case of an ESD_EV_CAN_ERROR_EXT now unconditionally supply
priv->bec.rxerr and priv->bec.txerr with REC and TEC.

Signed-off-by: Frank Jungclaus <frank.jungclaus@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 47 ++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 588caba1453b..09649a45d6ff 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -230,12 +230,23 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 	if (id == ESD_EV_CAN_ERROR_EXT) {
 		u8 state = msg->msg.rx.data[0];
 		u8 ecc   = msg->msg.rx.data[1];
-		u8 rxerr = msg->msg.rx.data[2];
-		u8 txerr = msg->msg.rx.data[3];
+
+		priv->bec.rxerr = msg->msg.rx.data[2];
+		priv->bec.txerr = msg->msg.rx.data[3];
 
 		netdev_dbg(priv->netdev,
 			   "CAN_ERR_EV_EXT: dlc=%#02x state=%02x ecc=%02x rec=%02x tec=%02x\n",
-			   msg->msg.rx.dlc, state, ecc, rxerr, txerr);
+			   msg->msg.rx.dlc, state, ecc, priv->bec.rxerr, priv->bec.txerr);
+
+		if (ecc) {
+			priv->can.can_stats.bus_error++;
+			stats->rx_errors++;
+		}
+
+		if (state == priv->old_state &&
+		    !(priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
+			/* Neither a state change nor active bus error reporting */
+			return;
 
 		skb = alloc_can_err_skb(priv->netdev, &cf);
 		if (skb == NULL) {
@@ -270,16 +281,14 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 				 * berr-counters might stay on values like
 				 * 95 forever ...
 				 */
-				txerr = 0;
-				rxerr = 0;
+				priv->bec.txerr = 0;
+				priv->bec.rxerr = 0;
 				break;
 			}
 		}
 
-		if (ecc) {
-			priv->can.can_stats.bus_error++;
-			stats->rx_errors++;
-
+		if (ecc && (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) {
+			/* Only if bus error reporting is active ... */
 			cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
 
 			/* Store error in CAN protocol (type) in data[2] */
@@ -301,29 +310,26 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 			if (!(ecc & SJA1000_ECC_DIR))
 				cf->data[2] |= CAN_ERR_PROT_TX;
 
-			/* Store error in CAN protocol (location) in data[3] */
+			/* Store error position in the bit stream of the CAN frame in data[3] */
 			cf->data[3] = ecc & SJA1000_ECC_SEG;
 
 			/* Store error status of CAN-controller in data[1] */
 			if (priv->can.state == CAN_STATE_ERROR_WARNING) {
-				if (txerr >= 96)
+				if (priv->bec.txerr >= 96)
 					cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;
-				if (rxerr >= 96)
+				if (priv->bec.rxerr >= 96)
 					cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
 			} else if (priv->can.state == CAN_STATE_ERROR_PASSIVE) {
-				if (txerr >= 128)
+				if (priv->bec.txerr >= 128)
 					cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
-				if (rxerr >= 128)
+				if (priv->bec.rxerr >= 128)
 					cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
 			}
 
-			cf->data[6] = txerr;
-			cf->data[7] = rxerr;
+			cf->data[6] = priv->bec.txerr;
+			cf->data[7] = priv->bec.rxerr;
 		}
 
-		priv->bec.txerr = txerr;
-		priv->bec.rxerr = rxerr;
-
 		netif_rx(skb);
 	}
 }
@@ -1021,7 +1027,8 @@ static int esd_usb_probe_one_net(struct usb_interface *intf, int index)
 
 	priv->can.state = CAN_STATE_STOPPED;
 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
-		CAN_CTRLMODE_CC_LEN8_DLC;
+				       CAN_CTRLMODE_CC_LEN8_DLC |
+				       CAN_CTRLMODE_BERR_REPORTING;
 
 	if (le16_to_cpu(dev->udev->descriptor.idProduct) ==
 	    USB_CANUSBM_PRODUCT_ID)
-- 
2.25.1