Re: [PATCH 1/2] net: can: c_can: Fix default pinmux glitch at init

[Roger Quadros]

On 07/07/15 18:49, Grygorii Strashko wrote:
> On 07/07/2015 05:37 PM, Roger Quadros wrote:
> > On 07/07/15 17:35, Roger Quadros wrote:
> > > On 07/07/15 17:33, Marc Kleine-Budde wrote:
> > > > On 07/07/2015 04:27 PM, Roger Quadros wrote:
> > > > > From: "J.D. Schroeder" <jay.schroeder@xxxxxxxxxx>
> > > > >
> > > > > The previous change 3973c526ae9c (net: can: c_can: Disable pins when
> > > > > CAN interface
> > > > > is down) causes a slight glitch on the pinctrl settings when used.
> > > > > Since
> > > > > commit ab78029 (drivers/pinctrl: grab default handles from device
> > > > > core),
> > > > > the device core will automatically set the default pins. This causes
> > > > > the pins to be momentarily set to the default and then to the sleep
> > > > > state in register_c_can_dev(). By adding an optional "enable" state,
> > > > > boards can set the default pin state to be disabled and avoid the
> > > > > glitch when the switch from default to sleep first occurs. If the
> > > > > "enable" state is not available c_can_pinctrl_select_state() falls
> > > > > back to using the "default" pinctrl state.
> > > > >
> > > > > [Roger Q] - Forward port to v4.2
> > > > >
> > > > > Signed-off-by: J.D. Schroeder <jay.schroeder@xxxxxxxxxx>
> > > > > Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> > > > > ---
> > > > >   drivers/net/can/c_can/c_can.c | 13 ++++++++++++-
> > > > >   1 file changed, 12 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/net/can/c_can/c_can.c
> > > > > b/drivers/net/can/c_can/c_can.c
> > > > > index 041525d..66e98e7 100644
> > > > > --- a/drivers/net/can/c_can/c_can.c
> > > > > +++ b/drivers/net/can/c_can/c_can.c
> > > > > @@ -605,7 +605,18 @@ static int c_can_start(struct net_device *dev)
> > > > >       priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > > > >
> > > > >       /* activate pins */
> > > > > -    pinctrl_pm_select_default_state(dev->dev.parent);
> > > > > +#ifdef CONFIG_PINCTRL
> > > >
> > > > Please remove the ifdef, AFAICS there are static inline noop functions
> > > > if CONFIG_PINCTRL switched off.
> > >
> > > yes, you are right.
> >
> > On second thoughts
> >
> > device->pins are not defined if CONFIG_PINCTRL is not set.
> > so we can't remove the #ifdef.
>
> May be you can use [devm_]pinctrl_get?

Why should we do that? The device core has already done the 
pinctrl_get() and it is available in device->pins->p.

cheers,
-roger

> > > > > +    if (priv->device->pins) {
> > > > > +        struct pinctrl_state *s;
> > > > > +
> > > > > +        /* Attempt to use "active" if available else use "default" */
> > > > > +        s = pinctrl_lookup_state(priv->device->pins->p, "active");
> > > > > +        if (!IS_ERR(s))
> > > > > +            pinctrl_select_state(priv->device->pins->p, s);
> > > > > +        else
> > > > > +            pinctrl_pm_select_default_state(dev->dev.parent);
> > > > > +    }
> > > > > +#endif
> > > > >       return 0;
> > > > >   }
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