[PATCH 5.13 016/104] can: peak_usb: pcan_usb_handle_bus_evt(): fix reading rxerr/txerr values

[Greg Kroah-Hartman]

From: Stephane Grosjean <s.grosjean@xxxxxxxxxxxxxxx>

commit 590eb2b7d8cfafb27e8108d52d4bf4850626d31d upstream.

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@xxxxxxxxxxxxxxx
Cc: linux-stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Stephane Grosjean <s.grosjean@xxxxxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/can/usb/peak_usb/pcan_usb.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- 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(struc
 
 	/* 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: