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

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 07/07/2015 04:27 PM, Roger Quadros wrote:
> From: "J.D. Schroeder" <jay.schroeder@garmin.com>
> 
> 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@garmin.com>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
>  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.

> +	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;
>  }
>  
> 

Marc

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