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

Message ID 1395054306-19058-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques March 17, 2014, 11:05 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-3.11.y-queue branch of the 3.11.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-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From bcba381376bf525c5e86e369aaf021062385c919 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>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/net/can/flexcan.c | 50 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 12 deletions(-)

--
1.9.0
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Patch

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 0bd9e2f..c9ea959 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
  *
@@ -266,26 +268,42 @@  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,
@@ -706,7 +724,9 @@  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);
@@ -946,12 +966,16 @@  static int register_flexcandev(struct net_device *dev)
 		goto out_disable_ipg;

 	/* 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);
@@ -968,14 +992,15 @@  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_disable_per;
+		goto out_chip_disable;
 	}

 	err = register_candev(dev);

- out_disable_per:
 	/* disable core and turn off clocks */
+ out_chip_disable:
 	flexcan_chip_disable(priv);
+ out_disable_per:
 	clk_disable_unprepare(priv->clk_per);
  out_disable_ipg:
 	clk_disable_unprepare(priv->clk_ipg);
@@ -1147,8 +1172,11 @@  static int flexcan_suspend(struct device *device)
 {
 	struct net_device *dev = dev_get_drvdata(device);
 	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);
@@ -1169,9 +1197,7 @@  static int flexcan_resume(struct device *device)
 		netif_device_attach(dev);
 		netif_start_queue(dev);
 	}
-	flexcan_chip_enable(priv);
-
-	return 0;
+	return flexcan_chip_enable(priv);
 }
 #endif /* CONFIG_PM_SLEEP */