[PATCH 4.4 56/73] can: flexcan: fix resume function

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fabio Estevam <fabio.estevam@xxxxxxx>

commit 4de349e786a3a2d51bd02d56f3de151bbc3c3df9 upstream.

On a imx6ul-pico board the following error is seen during system suspend:

dpm_run_callback(): platform_pm_resume+0x0/0x54 returns -110
PM: Device 2090000.flexcan failed to resume: error -110

The reason for this suspend error is because when the CAN interface is not
active the clocks are disabled and then flexcan_chip_enable() will
always fail due to a timeout error.

In order to fix this issue, only call flexcan_chip_enable/disable()
when the CAN interface is active.

Based on a patch from Dong Aisheng in the NXP kernel.

Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/can/flexcan.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1268,11 +1268,10 @@ static int __maybe_unused flexcan_suspen
 	struct flexcan_priv *priv = netdev_priv(dev);
 	int err;
 
-	err = flexcan_chip_disable(priv);
-	if (err)
-		return err;
-
 	if (netif_running(dev)) {
+		err = flexcan_chip_disable(priv);
+		if (err)
+			return err;
 		netif_stop_queue(dev);
 		netif_device_detach(dev);
 	}
@@ -1285,13 +1284,17 @@ static int __maybe_unused flexcan_resume
 {
 	struct net_device *dev = dev_get_drvdata(device);
 	struct flexcan_priv *priv = netdev_priv(dev);
+	int err;
 
 	priv->can.state = CAN_STATE_ERROR_ACTIVE;
 	if (netif_running(dev)) {
 		netif_device_attach(dev);
 		netif_start_queue(dev);
+		err = flexcan_chip_enable(priv);
+		if (err)
+			return err;
 	}
-	return flexcan_chip_enable(priv);
+	return 0;
 }
 
 static SIMPLE_DEV_PM_OPS(flexcan_pm_ops, flexcan_suspend, flexcan_resume);