linux-kernel - [PATCH 4.17 66/66] can: m_can.c: fix setup of CCCR register: clear CCCR NISO bit before checking can.ctrlmode

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Date:   Fri, 27 Jul 2018 11:45:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Roman Fietze <roman.fietze@...emotive.de>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 4.17 66/66] can: m_can.c: fix setup of CCCR register: clear CCCR NISO bit before checking can.ctrlmode

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Roman Fietze <roman.fietze@...emotive.de>

commit 393753b217f05474e714aea36c37501546ed1202 upstream.

Inside m_can_chip_config(), when setting up the new value of the CCCR,
the CCCR_NISO bit is not cleared like the others, CCCR_TEST, CCCR_MON,
CCCR_BRSE and CCCR_FDOE, before checking the can.ctrlmode bits for
CAN_CTRLMODE_FD_NON_ISO.

This way once the controller was configured for CAN_CTRLMODE_FD_NON_ISO,
this mode could never be cleared again.

This fix is only relevant for controllers with version 3.1.x or 3.2.x.
Older versions do not support NISO.

Signed-off-by: Roman Fietze <roman.fietze@...emotive.de>
Cc: linux-stable <stable@...r.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/can/m_can/m_can.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1111,7 +1111,8 @@ static void m_can_chip_config(struct net
 
 	} else {
 	/* Version 3.1.x or 3.2.x */
-		cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_BRSE | CCCR_FDOE);
+		cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_BRSE | CCCR_FDOE |
+			  CCCR_NISO);
 
 		/* Only 3.2.x has NISO Bit implemented */
 		if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)