netdev - [net 5/6] can: peak_usb: pcan_usb_handle_bus_evt(): fix reading rxerr/txerr values

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Message-Id: <20210724171947.547867-6-mkl@pengutronix.de>
Date:   Sat, 24 Jul 2021 19:19:46 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Stephane Grosjean <s.grosjean@...k-system.com>,
        linux-stable <stable@...r.kernel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [net 5/6] can: peak_usb: pcan_usb_handle_bus_evt(): fix reading rxerr/txerr values

From: Stephane Grosjean <s.grosjean@...k-system.com>

This patch fixes an incorrect way of reading error counters in messages
received for this purpose from the PCAN-USB interface. These messages
inform about the increase or decrease of the error counters, whose values
are placed in bytes 1 and 2 of the message data (not 0 and 1).

Fixes: ea8b33bde76c ("can: pcan_usb: add support of rxerr/txerr counters")
Link: https://lore.kernel.org/r/20210625130931.27438-4-s.grosjean@peak-system.com
Cc: linux-stable <stable@...r.kernel.org>
Signed-off-by: Stephane Grosjean <s.grosjean@...k-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/usb/peak_usb/pcan_usb.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 1d6f77252f01..899a3d21b77f 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -117,7 +117,8 @@
 #define PCAN_USB_BERR_MASK	(PCAN_USB_ERR_RXERR | PCAN_USB_ERR_TXERR)
 
 /* identify bus event packets with rx/tx error counters */
-#define PCAN_USB_ERR_CNT		0x80
+#define PCAN_USB_ERR_CNT_DEC		0x00	/* counters are decreasing */
+#define PCAN_USB_ERR_CNT_INC		0x80	/* counters are increasing */
 
 /* private to PCAN-USB adapter */
 struct pcan_usb {
@@ -608,11 +609,12 @@ static int pcan_usb_handle_bus_evt(struct pcan_usb_msg_context *mc, u8 ir)
 
 	/* acccording to the content of the packet */
 	switch (ir) {
-	case PCAN_USB_ERR_CNT:
+	case PCAN_USB_ERR_CNT_DEC:
+	case PCAN_USB_ERR_CNT_INC:
 
 		/* save rx/tx error counters from in the device context */
-		pdev->bec.rxerr = mc->ptr[0];
-		pdev->bec.txerr = mc->ptr[1];
+		pdev->bec.rxerr = mc->ptr[1];
+		pdev->bec.txerr = mc->ptr[2];
 		break;
 
 	default:
-- 
2.30.2