commit a125f73de40225692d7f0e722d452aad65467b8f
author Marc Kleine-Budde <mkl@pengutronix.de> Tue Sep 16 15:31:27 2014 +0200
committer Zefan Li <lizefan@huawei.com> Mon Dec 01 18:02:36 2014 +0800
tree 2e215716930b42a3f6c8b0c349ce4132425e57f5
parent a6cdbaecaa2575bd2f0dd290ff83cfe2dae06959

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@pengutronix.de>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/net/can/flexcan.c

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 681fb9c..b523e65 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -633,6 +633,9 @@
 	if (reg_iflag1 & (1 << FLEXCAN_TX_BUF_ID)) {
 		stats->tx_bytes += can_get_echo_skb(dev, 0);
 		stats->tx_packets++;
+		/* after sending a RTR frame mailbox is in RX mode */
+		flexcan_write(FLEXCAN_MB_CODE_TX_INACTIVE,
+			&regs->cantxfg[FLEXCAN_TX_BUF_ID].can_ctrl);
 		flexcan_write((1 << FLEXCAN_TX_BUF_ID), &regs->iflag1);
 		netif_wake_queue(dev);
 	}