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

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Date:	Thu, 9 Jul 2015 14:19:49 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Marc Kleine-Budde <mkl@...gutronix.de>,
	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 01:59 PM, Marc Kleine-Budde wrote:
> 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?

Not sure I can ack overall patch - is up to can driver maintainer
for this part Reviewed-by: Grygorii Strashko <grygorii.strashko@...com>

-- 
regards,
-grygorii
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