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

[ Upstream commit 918ee4911f7a41fb4505dff877c1d7f9f64eb43e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/can/usb/esd_usb2.c b/drivers/net/can/usb/esd_usb2.c
index c6068a2..9ed048c 100644 (file)
--- a/drivers/net/can/usb/esd_usb2.c
+++ b/drivers/net/can/usb/esd_usb2.c
@@ -227,6 +227,10 @@ static void esd_usb2_rx_event(struct esd_usb2_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++;
@@ -253,6 +257,8 @@ static void esd_usb2_rx_event(struct esd_usb2_net_priv *priv,
                                break;
                        default:
                                priv->can.state = CAN_STATE_ERROR_ACTIVE;
+                               txerr = 0;
+                               rxerr = 0;
                                break;
                        }
                } else {