[PATCH v6 4/7] can: kvaser_usb: Fix state handling upon BUS_ERROR events

Ahmed S. Darwish
2015-01-26T05:25:51Z

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

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

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index 55407b9..7af379c 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -698,9 +698,7 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
}

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;
@@ -710,7 +708,8 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,

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;

--
1.7.7.6