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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexander Stein <alexander.stein@systec-electronic.com>,
        Pankaj Bansal <pankaj.bansal@nxp.com>,
        Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH 4.19 048/110] can: flexcan: Unlock the MB unconditionally
Date:   Thu, 29 Nov 2018 15:12:19 +0100
Message-Id: <20181129135923.203428995@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Pankaj Bansal <pankaj.bansal@nxp.com>

commit 5178b7cd8e42448b1041716f124734eaaa36ca50 upstream.

Unlock the MB irrespective of reception method being FIFO or timestamp
based. It is optional but recommended to unlock Mailbox as soon as
possible and make it available for reception.

Reported-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/can/flexcan.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -720,9 +720,14 @@ static unsigned int flexcan_mailbox_read
 			priv->write(BIT(n - 32), &regs->iflag2);
 	} else {
 		priv->write(FLEXCAN_IFLAG_RX_FIFO_AVAILABLE, &regs->iflag1);
-		priv->read(&regs->timer);
 	}
 
+	/* Read the Free Running Timer. It is optional but recommended
+	 * to unlock Mailbox as soon as possible and make it available
+	 * for reception.
+	 */
+	priv->read(&regs->timer);
+
 	return 1;
 }