RE: [PATCH V2 4/4] can: flexcan: add LPSR mode support

[Joakim Zhang <qiangqing.zhang@xxxxxxx>]

> -----Original Message-----
> From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> Sent: 2019年12月4日 17:21
> To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; sean@xxxxxxxxxx;
> linux-can@xxxxxxxxxxxxxxx
> Cc: dl-linux-imx <linux-imx@xxxxxxx>; netdev@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH V2 4/4] can: flexcan: add LPSR mode support
> 
> On 11/27/19 6:56 AM, Joakim Zhang wrote:
> > For i.MX7D LPSR mode, the controller will lost power and got the
> > configuration state lost after system resume back. (coming i.MX8QM/QXP
> > will also completely power off the domain, the controller state will
> > be lost and needs restore).
> > So we need to set pinctrl state again and re-start chip to do
> > re-configuration after resume.
> >
> > For wakeup case, it should not set pinctrl to sleep state by
> > pinctrl_pm_select_sleep_state.
> > For interface is not up before suspend case, we don't need
> > re-configure as it will be configured by user later by interface up.
> >
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> > ------
> > ChangeLog:
> > 	V1->V2: no change.
> > ---
> >  drivers/net/can/flexcan.c | 21 ++++++++++++++-------
> >  1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> > index d178146b3da5..d1509cffdd24 100644
> > --- a/drivers/net/can/flexcan.c
> > +++ b/drivers/net/can/flexcan.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/pm_runtime.h>
> >  #include <linux/regulator/consumer.h>
> > +#include <linux/pinctrl/consumer.h>
> >  #include <linux/regmap.h>
> >
> >  #define DRV_NAME			"flexcan"
> > @@ -1707,7 +1708,7 @@ static int __maybe_unused
> flexcan_suspend(struct
> > device *device)  {
> >  	struct net_device *dev = dev_get_drvdata(device);
> >  	struct flexcan_priv *priv = netdev_priv(dev);
> > -	int err = 0;
> > +	int err;
> >
> >  	if (netif_running(dev)) {
> >  		/* if wakeup is enabled, enter stop mode @@ -1719,25 +1720,27
> @@
> > static int __maybe_unused flexcan_suspend(struct device *device)
> >  			if (err)
> >  				return err;
> >  		} else {
> > -			err = flexcan_chip_disable(priv);
> > +			flexcan_chip_stop(dev);
> 
> chip_stop calls chip_disable, but doesn't propagate the error value.
> Please create a seperate patch to propagate the error value of chip_stop().

Hi Marc,

I found not only chip_disable should propagate the error value, others chip_freeze, transceiver_disable also need.'
I cook a patch below, is it fine for you?

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 19602b77907f..c5e4b6928dee 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1263,14 +1263,19 @@ static int flexcan_chip_start(struct net_device *dev)
  *
  * this functions is entered with clocks enabled
  */
-static void flexcan_chip_stop(struct net_device *dev)
+static int flexcan_chip_stop(struct net_device *dev)
 {
        struct flexcan_priv *priv = netdev_priv(dev);
        struct flexcan_regs __iomem *regs = priv->regs;
+       int err;

        /* freeze + disable module */
-       flexcan_chip_freeze(priv);
-       flexcan_chip_disable(priv);
+       err = flexcan_chip_freeze(priv);
+       if (err)
+               return err;
+       err = flexcan_chip_disable(priv);
+       if (err)
+               goto out_chip_unfreeze;

        /* Disable all interrupts */
        priv->write(0, &regs->imask2);
@@ -1278,8 +1283,19 @@ static void flexcan_chip_stop(struct net_device *dev)
        priv->write(priv->reg_ctrl_default & ~FLEXCAN_CTRL_ERR_ALL,
                    &regs->ctrl);

-       flexcan_transceiver_disable(priv);
+       err = flexcan_transceiver_disable(priv);
+       if (err)
+               goto out_chip_enable;
+
        priv->can.state = CAN_STATE_STOPPED;
+
+       return 0;
+
+out_chip_enable:
+       flexcan_chip_enable(priv);
+out_chip_unfreeze:
+       flexcan_chip_unfreeze(priv);
+       return err;
 }

 static int flexcan_open(struct net_device *dev)

Best Regards,
Joakim Zhang
> Marc
> 
> --
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