can: peak_usb: pcan_usb_handle_bus_evt(): fix reading rxerr/txerr values

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@vger.kernel.org>
Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 1d6f772..899a3d2 100644 (file)
--- 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: