linux-kernel - Re: [PATCH 3/4] extcon: usb-gpio: make debounce value configurable in devicetree

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Message-id: <551A9039.1010705@samsung.com>
Date:	Tue, 31 Mar 2015 14:16:57 +0200
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	Roger Quadros <rogerq@...com>, cw00.choi@...sung.com
Cc:	myungjoo.ham@...sung.com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com
Subject: Re: [PATCH 3/4] extcon: usb-gpio: make debounce value configurable in
 devicetree

On 03/31/2015 11:30 AM, Roger Quadros wrote:
> On 31/03/15 10:46, Robert Baldyga wrote:
>> This patch adds devicetree property for setting debounce value. It allows
>> to set debounce time shorter or longer depending on the needs of given
>> platform.
>>
>> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
>> ---
>>  drivers/extcon/extcon-usb-gpio.c | 14 +++++++++-----
>>  1 file changed, 9 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
>> index 02ff40e..86e3ece 100644
>> --- a/drivers/extcon/extcon-usb-gpio.c
>> +++ b/drivers/extcon/extcon-usb-gpio.c
>> @@ -130,6 +130,7 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>  	struct device *dev = &pdev->dev;
>>  	struct device_node *np = dev->of_node;
>>  	struct usb_extcon_info *info;
>> +	u32 debounce;
>>  	int ret;
>>  
>>  	if (!np)
>> @@ -140,6 +141,11 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>  		return -ENOMEM;
>>  
>>  	info->dev = dev;
>> +
>> +	ret = of_property_read_u32(np, "debounce", &debounce);
>> +	if (ret < 0)
>> +		debounce = USB_GPIO_DEBOUNCE_MS;
>> +
> 
> Should we sanity check debounce value provided by device tree?
> e.g. if it is greater than USB_GPIO_DEBOUNCE_MAX then we error out.
> MAX could be 100 or 250ms.
> 

None of extcon drivers do such thing, so I suppose it's up to devicetree
to supply reasonable value here.

>>  	info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id");
>>  	info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus");
>>  
>> @@ -161,16 +167,14 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>  	}
>>  
>>  	if (info->id_gpiod)
>> -		ret = gpiod_set_debounce(info->id_gpiod,
>> -			USB_GPIO_DEBOUNCE_MS * 1000);
>> +		ret = gpiod_set_debounce(info->id_gpiod, debounce * 1000);
>>  	if (!ret && info->vbus_gpiod) {
>> -		ret = gpiod_set_debounce(info->vbus_gpiod,
>> -			USB_GPIO_DEBOUNCE_MS * 1000);
>> +		ret = gpiod_set_debounce(info->vbus_gpiod, debounce * 1000);
>>  		if (ret < 0 && info->id_gpiod)
>>  			gpiod_set_debounce(info->vbus_gpiod, 0);
>>  	}
>>  	if (ret < 0)
>> -		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
>> +		info->debounce_jiffies = msecs_to_jiffies(debounce);
>>  
>>  	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
>>  
>>

Best regards,
Robert Baldyga

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