[3.16.y-ckt stable] Patch "can: kvaser_usb: Fix state handling upon BUS_ERROR events" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    can: kvaser_usb: Fix state handling upon BUS_ERROR events

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From c42be90e5004139eaea6c0a9ad49f5300eb2eddc Mon Sep 17 00:00:00 2001
From: "Ahmed S. Darwish" <ahmed.darwish at valeo.com>
Date: Mon, 26 Jan 2015 07:25:43 +0200
Subject: can: kvaser_usb: Fix state handling upon BUS_ERROR events

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 at valeo.com>
Signed-off-by: Marc Kleine-Budde <mkl at pengutronix.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/can/usb/kvaser_usb.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index f85f02150877..8b255e777cc7 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;

--
2.1.4