commit fc05b884a31dbf259cc73cc856e634ec3acbebb6
author David Jander <david@protonic.nl> Wed Aug 27 11:58:05 2014 +0200
committer Marc Kleine-Budde <mkl@pengutronix.de> Thu Sep 18 11:15:15 2014 +0200
tree 13a85ec5cd1e282ba0afa03bf9caaf6ac660b288
parent c32fe4ad3e4861b2bfa1f44114c564935a123dda

can: flexcan: correctly initialize mailboxes

Apparently mailboxes may contain random data at startup, causing some of them
being prepared for message reception. This causes overruns being missed or even
confusing the IRQ check for trasmitted messages, increasing the transmit
counter instead of the error counter.

This patch initializes all mailboxes after the FIFO as RX_INACTIVE.

Signed-off-by: David Jander <david@protonic.nl>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/flexcan.c

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 76dcbca..fc076952 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -812,6 +812,7 @@
 	struct flexcan_regs __iomem *regs = priv->base;
 	int err;
 	u32 reg_mcr, reg_ctrl;
+	int i;
 
 	/* enable module */
 	err = flexcan_chip_enable(priv);
@@ -878,6 +879,12 @@
 	netdev_dbg(dev, "%s: writing ctrl=0x%08x", __func__, reg_ctrl);
 	flexcan_write(reg_ctrl, &regs->ctrl);
 
+	/* clear and invalidate all mailboxes first */
+	for (i = FLEXCAN_TX_BUF_ID; i < ARRAY_SIZE(regs->cantxfg); i++) {
+		flexcan_write(FLEXCAN_MB_CODE_RX_INACTIVE,
+			      &regs->cantxfg[i].can_ctrl);
+	}
+
 	/* mark TX mailbox as INACTIVE */
 	flexcan_write(FLEXCAN_MB_CODE_TX_INACTIVE,
 		      &regs->cantxfg[FLEXCAN_TX_BUF_ID].can_ctrl);