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

[Roger Quadros <rogerq@ti.com>]

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@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.
>
> 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.

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;
>>>   }
>>>
>>>
>>
>> Marc
>>
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