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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 v2 1/1] can: esd_usb: Allow REC and TEC to return to zero
Date:   Wed, 30 Nov 2022 21:22:42 +0100
Message-Id: <20221130202242.3998219-2-frank.jungclaus@esd.eu>
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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>
---
 drivers/net/can/usb/esd_usb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 1bcfad11b1e4..acfc439a325c 100644
--- 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 {
-- 
2.25.1