[PATCH 3.14 10/33] can: kvaser_usb: Fix state handling upon BUS_ERROR events

Greg Kroah-Hartman
2015-02-03T23:18:55Z

From: "Ahmed S. Darwish" <ahmed.darwish@valeo.com>

commit e638642b08c170d2021b706f0b1c4f4ae93d8cbd upstream.

While being in an ERROR_WARNING state, and receiving further
bus error events with error counters still in the ERROR_WARNING
range of 97-127 inclusive, the state handling code erroneously
reverts back to ERROR_ACTIVE.

Per the CAN standard, only revert to ERROR_ACTIVE when the
error counters are less than 96.

Moreover, in certain Kvaser models, the BUS_ERROR flag is
always set along with undefined bits in the M16C status
register. Thus use bitwise operators instead of full equality
for checking that register against bus errors.

Signed-off-by: Ahmed S. Darwish <ahmed.darwish@valeo.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/usb/kvaser_usb.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -689,9 +689,7 @@ static void kvaser_usb_rx_error(const st
}

new_state = CAN_STATE_ERROR_PASSIVE;
- }
-
- if (status == M16C_STATE_BUS_ERROR) {
+ } else if (status & M16C_STATE_BUS_ERROR) {
if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
((txerr >= 96) || (rxerr >= 96))) {
cf->can_id |= CAN_ERR_CRTL;
@@ -701,7 +699,8 @@ static void kvaser_usb_rx_error(const st

priv->can.can_stats.error_warning++;
new_state = CAN_STATE_ERROR_WARNING;
- } else if (priv->can.state > CAN_STATE_ERROR_ACTIVE) {
+ } else if ((priv->can.state > CAN_STATE_ERROR_ACTIVE) &&
+ ((txerr < 96) && (rxerr < 96))) {
cf->can_id |= CAN_ERR_PROT;
cf->data[2] = CAN_ERR_PROT_ACTIVE;