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[3.8.y.z,extended,stable] Patch "can: flexcan: fix transition from and to low power mode in" has been added to staging queue

Message ID 1395968036-11296-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa March 28, 2014, 12:53 a.m. UTC 
This is a note to let you know that I have just added a patch titled

    can: flexcan: fix transition from and to low power mode in

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 3.8.13.21.

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

------

From 428cfe492c716dc2619e7cc77ed4a967bef715f8 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Fri, 28 Feb 2014 15:30:18 +0100
Subject: can: flexcan: fix transition from and to low power mode in
 chip_{en,dis}able

commit 9b00b300e7bce032c467c36ca47fe2a776887fc2 upstream.

In flexcan_chip_enable() and flexcan_chip_disable() fixed delays are used.
Experiments have shown that the transition from and to low power mode may take
several microseconds.

This patch adds a while loop which polls the Low Power Mode ACK bit (LPM_ACK)
that indicates a successfull mode change. If the function runs into a timeout a
error value is returned.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/net/can/flexcan.c | 50 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 12 deletions(-)

--
1.8.3.2
diff mbox

Patch

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 9771652..275b721 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -144,6 +144,8 @@ 

 #define FLEXCAN_MB_CODE_MASK		(0xf0ffffff)

+#define FLEXCAN_TIMEOUT_US             (50)
+
 /*
  * FLEXCAN hardware feature flags
  *
@@ -274,26 +276,42 @@  static inline int flexcan_has_and_handle_berr(const struct flexcan_priv *priv,
 		(reg_esr & FLEXCAN_ESR_ERR_BUS);
 }

-static inline void flexcan_chip_enable(struct flexcan_priv *priv)
+static int flexcan_chip_enable(struct flexcan_priv *priv)
 {
 	struct flexcan_regs __iomem *regs = priv->base;
+	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
 	u32 reg;

 	reg = flexcan_read(&regs->mcr);
 	reg &= ~FLEXCAN_MCR_MDIS;
 	flexcan_write(reg, &regs->mcr);

-	udelay(10);
+	while (timeout-- && (flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+		usleep_range(10, 20);
+
+	if (flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK)
+		return -ETIMEDOUT;
+
+	return 0;
 }

-static inline void flexcan_chip_disable(struct flexcan_priv *priv)
+static int flexcan_chip_disable(struct flexcan_priv *priv)
 {
 	struct flexcan_regs __iomem *regs = priv->base;
+	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
 	u32 reg;

 	reg = flexcan_read(&regs->mcr);
 	reg |= FLEXCAN_MCR_MDIS;
 	flexcan_write(reg, &regs->mcr);
+
+	while (timeout-- && !(flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+		usleep_range(10, 20);
+
+	if (!(flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+		return -ETIMEDOUT;
+
+	return 0;
 }

 static int flexcan_get_berr_counter(const struct net_device *dev,
@@ -711,7 +729,9 @@  static int flexcan_chip_start(struct net_device *dev)
 	u32 reg_mcr, reg_ctrl;

 	/* enable module */
-	flexcan_chip_enable(priv);
+	err = flexcan_chip_enable(priv);
+	if (err)
+		return err;

 	/* soft reset */
 	flexcan_write(FLEXCAN_MCR_SOFTRST, &regs->mcr);
@@ -930,12 +950,16 @@  static int register_flexcandev(struct net_device *dev)
 	clk_prepare_enable(priv->clk_per);

 	/* select "bus clock", chip must be disabled */
-	flexcan_chip_disable(priv);
+	err = flexcan_chip_disable(priv);
+	if (err)
+		goto out_disable_per;
 	reg = flexcan_read(&regs->ctrl);
 	reg |= FLEXCAN_CTRL_CLK_SRC;
 	flexcan_write(reg, &regs->ctrl);

-	flexcan_chip_enable(priv);
+	err = flexcan_chip_enable(priv);
+	if (err)
+		goto out_chip_disable;

 	/* set freeze, halt and activate FIFO, restrict register access */
 	reg = flexcan_read(&regs->mcr);
@@ -952,14 +976,15 @@  static int register_flexcandev(struct net_device *dev)
 	if (!(reg & FLEXCAN_MCR_FEN)) {
 		netdev_err(dev, "Could not enable RX FIFO, unsupported core\n");
 		err = -ENODEV;
-		goto out;
+		goto out_chip_disable;
 	}

 	err = register_candev(dev);

- out:
 	/* disable core and turn off clocks */
+ out_chip_disable:
 	flexcan_chip_disable(priv);
+ out_disable_per:
 	clk_disable_unprepare(priv->clk_per);
 	clk_disable_unprepare(priv->clk_ipg);

@@ -1130,8 +1155,11 @@  static int flexcan_suspend(struct platform_device *pdev, pm_message_t state)
 {
 	struct net_device *dev = platform_get_drvdata(pdev);
 	struct flexcan_priv *priv = netdev_priv(dev);
+	int err;

-	flexcan_chip_disable(priv);
+	err = flexcan_chip_disable(priv);
+	if (err)
+		return err;

 	if (netif_running(dev)) {
 		netif_stop_queue(dev);
@@ -1152,9 +1180,7 @@  static int flexcan_resume(struct platform_device *pdev)
 		netif_device_attach(dev);
 		netif_start_queue(dev);
 	}
-	flexcan_chip_enable(priv);
-
-	return 0;
+	return flexcan_chip_enable(priv);
 }
 #else
 #define flexcan_suspend NULL