[PATCH 3.13 123/163] can: flexcan: put TX mailbox into TX_INACTIVE mode after tx-complete

From: Kamal Mostafa
Date: Thu Oct 09 2014 - 17:34:25 EST -stable review patch. If anyone has any objections, please let me know.


From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
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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