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[3.8.y.z,extended,stable] Patch "can: flexcan: flexcan_chip_start: fix regression, mark one MB for TX" has been added to staging queue

Message ID 1382997566-20322-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Oct. 28, 2013, 9:59 p.m. UTC
This is a note to let you know that I have just added a patch titled

    can: flexcan: flexcan_chip_start: fix regression, mark one MB for TX

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.12.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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From afd273a974b9cf29c43fa84ae20f265f0a3cc638 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Fri, 4 Oct 2013 10:52:36 +0200
Subject: can: flexcan: flexcan_chip_start: fix regression, mark one MB for TX
 and abort pending TX
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit d5a7b406c529e4595ce03dc8f6dcf7fa36f106fa upstream.

In patch

    0d1862e can: flexcan: fix flexcan_chip_start() on imx6

the loop in flexcan_chip_start() that iterates over all mailboxes after the
soft reset of the CAN core was removed. This loop put all mailboxes (even the
ones marked as reserved 1...7) into EMPTY/INACTIVE mode. On mailboxes 8...63,
this aborts any pending TX messages.

After a cold boot there is random garbage in the mailboxes, which leads to
spontaneous transmit of CAN frames during first activation. Further if the
interface was disabled with a pending message (usually due to an error
condition on the CAN bus), this message is retransmitted after enabling the
interface again.

This patch fixes the regression by:
1) Limiting the maximum number of used mailboxes to 8, 0...7 are used by the RX
FIFO, 8 is used by TX.
2) Marking the TX mailbox as EMPTY/INACTIVE, so that any pending TX of that
mailbox is aborted.

Cc: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/net/can/flexcan.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--
1.8.1.2
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Patch

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 15d5abb..5817a39 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -62,7 +62,7 @@ 
 #define FLEXCAN_MCR_BCC			BIT(16)
 #define FLEXCAN_MCR_LPRIO_EN		BIT(13)
 #define FLEXCAN_MCR_AEN			BIT(12)
-#define FLEXCAN_MCR_MAXMB(x)		((x) & 0xf)
+#define FLEXCAN_MCR_MAXMB(x)		((x) & 0x1f)
 #define FLEXCAN_MCR_IDAM_A		(0 << 8)
 #define FLEXCAN_MCR_IDAM_B		(1 << 8)
 #define FLEXCAN_MCR_IDAM_C		(2 << 8)
@@ -740,9 +740,11 @@  static int flexcan_chip_start(struct net_device *dev)
 	 *
 	 */
 	reg_mcr = flexcan_read(&regs->mcr);
+	reg_mcr &= ~FLEXCAN_MCR_MAXMB(0xff);
 	reg_mcr |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_FEN | FLEXCAN_MCR_HALT |
 		FLEXCAN_MCR_SUPV | FLEXCAN_MCR_WRN_EN |
-		FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_SRX_DIS;
+		FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_SRX_DIS |
+		FLEXCAN_MCR_MAXMB(FLEXCAN_TX_BUF_ID);
 	netdev_dbg(dev, "%s: writing mcr=0x%08x", __func__, reg_mcr);
 	flexcan_write(reg_mcr, &regs->mcr);

@@ -776,6 +778,10 @@  static int flexcan_chip_start(struct net_device *dev)
 	netdev_dbg(dev, "%s: writing ctrl=0x%08x", __func__, reg_ctrl);
 	flexcan_write(reg_ctrl, &regs->ctrl);

+	/* Abort any pending TX, mark Mailbox as INACTIVE */
+	flexcan_write(FLEXCAN_MB_CNT_CODE(0x4),
+		      &regs->cantxfg[FLEXCAN_TX_BUF_ID].can_ctrl);
+
 	/* acceptance mask/acceptance code (accept everything) */
 	flexcan_write(0x0, &regs->rxgmask);
 	flexcan_write(0x0, &regs->rx14mask);