[3.13.y.z extended stable] Patch "can: flexcan: put TX mailbox into TX_INACTIVE mode after tx-complete" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu Oct 9 20:51:41 UTC 2014

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

    can: flexcan: put TX mailbox into TX_INACTIVE mode after tx-complete

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

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

For more information about the 3.13.y.z tree, see



>From 71a05f0fddd4c83871b159f77f5f52667373b7a4 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl at pengutronix.de>
Date: Tue, 16 Sep 2014 15:31:27 +0200
Subject: can: flexcan: put TX mailbox into TX_INACTIVE mode after tx-complete

commit de5944883ebbedbf5adc8497659772f5da7b7d72 upstream.

After sending a RTR frame the TX mailbox becomes a RX_EMPTY mailbox. To avoid
side effects when the RX-FIFO is full, this patch puts the TX mailbox into
TX_INACTIVE mode in the transmission complete interrupt handler. This, of
course, leaves a race window between the actual completion of the transmission
and the handling of tx-complete interrupt. However this is the best we can do
without busy polling the tx complete interrupt.

Signed-off-by: Marc Kleine-Budde <mkl at pengutronix.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/net/can/flexcan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 3a1859b..deea3a9 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -702,6 +702,9 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
 		stats->tx_bytes += can_get_echo_skb(dev, 0);
 		can_led_event(dev, CAN_LED_EVENT_TX);
+		/* after sending a RTR frame mailbox is in RX mode */
+			      &regs->cantxfg[FLEXCAN_TX_BUF_ID].can_ctrl);
 		flexcan_write((1 << FLEXCAN_TX_BUF_ID), &regs->iflag1);

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