can: esd_usb: Allow REC and TEC to return to zero

We don't get any further EVENT from an esd CAN USB device for changes
on REC or TEC while those counters converge to 0 (with ecc == 0). So
when handling the "Back to Error Active"-event force txerr = rxerr =
0, otherwise the berr-counters might stay on values like 95 forever.

Also, to make life easier during the ongoing development a
netdev_dbg() has been introduced to allow dumping error events send by
an esd CAN USB device.

Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
Signed-off-by: Frank Jungclaus <frank.jungclaus@esd.eu>
Link: https://lore.kernel.org/all/20221130202242.3998219-2-frank.jungclaus@esd.eu
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 81b88e9e5bdc09f0305d85d132cd5d502afd324c..42323f5e6f3a010609b7529bb6cfec2b53860228 100644 (file)
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -234,6 +234,10 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
                u8 rxerr = msg->msg.rx.data[2];
                u8 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);
+
                skb = alloc_can_err_skb(priv->netdev, &cf);
                if (skb == NULL) {
                        stats->rx_dropped++;
@@ -260,6 +264,8 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
                                break;
                        default:
                                priv->can.state = CAN_STATE_ERROR_ACTIVE;
+                               txerr = 0;
+                               rxerr = 0;
                                break;
                        }
                } else {