linux-kernel - Re: [PATCH v2 1/2] net: can: c_can: Fix default pinmux glitch at init

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Message-ID: <559E5412.5090604@pengutronix.de>
Date:	Thu, 9 Jul 2015 12:59:30 +0200
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Grygorii Strashko <grygorii.strashko@...com>,
	Roger Quadros <rogerq@...com>, wg@...ndegger.com,
	tony@...mide.com
Cc:	jay.schroeder@...min.com, linux-can@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] net: can: c_can: Fix default pinmux glitch at init

On 07/09/2015 12:58 PM, Grygorii Strashko wrote:
> On 07/08/2015 02:38 PM, Roger Quadros wrote:
>> From: "J.D. Schroeder" <jay.schroeder@...min.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 and use pinctrl_get_select().
>>
>> Signed-off-by: J.D. Schroeder <jay.schroeder@...min.com>
>> Signed-off-by: Roger Quadros <rogerq@...com>
>> ---
>>   drivers/net/can/c_can/c_can.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
>> index 041525d..5d214d1 100644
>> --- a/drivers/net/can/c_can/c_can.c
>> +++ b/drivers/net/can/c_can/c_can.c
>> @@ -592,6 +592,7 @@ static int c_can_start(struct net_device *dev)
>>   {
>>   	struct c_can_priv *priv = netdev_priv(dev);
>>   	int err;
>> +	struct pinctrl *p;
>>
>>   	/* basic c_can configuration */
>>   	err = c_can_chip_config(dev);
>> @@ -604,8 +605,13 @@ 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);
>> +	/* Attempt to use "active" if available else use "default" */
>> +	p = pinctrl_get_select(priv->device, "active");
>> +	if (!IS_ERR(p))
>> +		pinctrl_put(p);
>> +	else
>> +		pinctrl_pm_select_default_state(priv->device);
>> +
> 
> Thanks. This part looks good to me now.

Is this an Acked-by?

Marc

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