linux-kernel - [PATCH RESEND 1/1] can: esd_usb: Allow REC and TEC to return to zero

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Message-Id: <20221124203806.3034897-2-frank.jungclaus@esd.eu>
Date:   Thu, 24 Nov 2022 21:38:06 +0100
From:   Frank Jungclaus <frank.jungclaus@....eu>
To:     linux-can@...r.kernel.org, Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>
Cc:     Stefan Mätje <stefan.maetje@....eu>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Frank Jungclaus <frank.jungclaus@....eu>
Subject: [PATCH RESEND 1/1] 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.

Signed-off-by: Frank Jungclaus <frank.jungclaus@....eu>
---
 drivers/net/can/usb/esd_usb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 1bcfad11b1e4..da24c649aadd 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -230,10 +230,14 @@ 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 ecc   = msg->msg.rx.data[1];
 		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