Date:	Thu, 20 Mar 2014 15:56:22 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	gregkh@...uxfoundation.org, balbi@...com, myungjoo.ham@...sung.com,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH 1/2] extcon: of: Remove unnecessary function call by using
 the name of device_node

Hi,

On 03/20/2014 02:20 PM, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Thursday 20 March 2014 07:52 AM, Chanwoo Choi wrote:
>> Hi,
>>
>> On 03/19/2014 09:08 PM, Kishon Vijay Abraham I wrote:
>>> Hi,
>>>
>>> On Tuesday 18 March 2014 05:34 PM, Chanwoo Choi wrote:
>>>> This patch remove unnecessary function call in of_extcon_get_extcon_dev()
>>>> by using the name of device_node structure.
>>>>
>>>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>>>> ---
>>>>  drivers/extcon/of_extcon.c | 12 ++----------
>>>>  1 file changed, 2 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/extcon/of_extcon.c b/drivers/extcon/of_extcon.c
>>>> index 72173ec..0a29f82 100644
>>>> --- a/drivers/extcon/of_extcon.c
>>>> +++ b/drivers/extcon/of_extcon.c
>>>> @@ -32,7 +32,6 @@ struct extcon_dev *of_extcon_get_extcon_dev(struct device *dev, int index)
>>>>  {
>>>>  	struct device_node *node;
>>>>  	struct extcon_dev *edev;
>>>> -	struct platform_device *extcon_parent_dev;
>>>>  
>>>>  	if (!dev->of_node) {
>>>>  		dev_dbg(dev, "device does not have a device node entry\n");
>>>> @@ -46,16 +45,9 @@ struct extcon_dev *of_extcon_get_extcon_dev(struct device *dev, int index)
>>>>  		return ERR_PTR(-ENODEV);
>>>>  	}
>>>>  
>>>> -	extcon_parent_dev = of_find_device_by_node(node);
>>>> -	if (!extcon_parent_dev) {
>>>> -		dev_dbg(dev, "unable to find device by node\n");
>>>> -		return ERR_PTR(-EPROBE_DEFER);
>>>> -	}
>>>> -
>>>> -	edev = extcon_get_extcon_dev(dev_name(&extcon_parent_dev->dev));
>>>> +	edev = extcon_get_extcon_dev(node->name);
>>>
>>> Since you no longer want to use device names I think you should add this too to
>>> warn users if they rely on using the device name.
>>
>> Previous of_extcon_get_extcon_dev() support only platform device using of_find_device_by_node.
>>
>> If extcon device is based on i2c/spi/pci and so on, of_extcon_get_extcon_dev() can't
>> find device instance for device name. So, I change device name from the name of platform device
>> to the name of dt node.
> 
> That's fine. But we have to fix extcon_dev_register() too, to not use device
> names right? We have to warn extcon users not to use device names right?

I don't think so. extcon_get_edev_by_phandle() shows wrong node->name as following:
The consumer could detect the cause of problem which can't get extcon device after
checking error log message.

	edev = extcon_get_extcon_dev(node->name);
	if (!edev) {
		dev_err(dev, "unable to get extcon device : %s\n", node->name);
		return ERR_PTR(-ENODEV);
	}

I don't want to add more log message.

>>
>>
>>> diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c
>>> index bc4c789..025eb39 100644
>>> --- a/drivers/extcon/extcon-class.c
>>> +++ b/drivers/extcon/extcon-class.c
>>> @@ -601,7 +601,6 @@ int extcon_dev_register(struct extcon_dev *edev)
>>>         edev->dev.class = extcon_class;
>>>         edev->dev.release = extcon_dev_release;
>>>
>>> -       edev->name = edev->name ? edev->name : dev_name(edev->dev.parent);
>>> //The user should always pass the 'name' as we no longer use device name while
>>> getting extcon device. And this name should also be the 'node' name?
>>>         if (IS_ERR_OR_NULL(edev->name)) {
>>>                 dev_err(&edev->dev,
>>>                         "extcon device name is null\n");
>>>
>>> Btw changing to node name from device name breaks dwc3 in OMAP5 and you would
>>> need this too..
>>>
>>> diff --git a/drivers/extcon/extcon-palmas.c b/drivers/extcon/extcon-palmas.c
>>> index 2aea4bc..cea8cd3 100644
>>> --- a/drivers/extcon/extcon-palmas.c
>>> +++ b/drivers/extcon/extcon-palmas.c
>>> @@ -188,6 +188,7 @@ static int palmas_usb_probe(struct platform_device *pdev)
>>>
>>>         palmas_usb->edev.supported_cable = palmas_extcon_cable;
>>>         palmas_usb->edev.dev.parent = palmas_usb->dev;
>>> +       palmas_usb->edev.name = "palmas_usb";
>>>         palmas_usb->edev.mutually_exclusive = mutually_exclusive;
>>>
>>>         status = extcon_dev_register(&palmas_usb->edev);
>>>
>>> Cheers
>>> Kishon
>>>
>>
>> If node name is same as extcon device name, don't need some modification.
>> Also, you can modify node name in some OMAP dts file insead of modification of extcon-palmas.c
> 
> node name in OMAP dts is already 'palmas_usb'. But since we were not setting
> 'edev.name' in extcon-palmas.c, extcon_dev_register used device name of palmas
> (palmas_usb.7 in my case). So extcon-palmas.c needs the fix.

For example,
I used extcon provider/consumer driver in dts as following:
extcon-max14577.c set device name as edev->name and then dt node name of max14577
set "max14577-muic" which is same as device name(dev_name(&pdev->dev)).

I don't need to modify extcon-max14577.c

In drivers/extcon/extcon-max14577.c
	...
	info->edev->name = dev_name(&pdev->dev);
	...
In dts.
	i2c@...80000 {
		.....
		max14577@25 {
			.....
			muic: max14577-muic {
				compatible = "maxim,max14577-muic";
			};
			....
		};
	};

	hsotg@...80000 {
		.....
		extcon = <&muic>;
	};


Thanks,
Chanwoo Choi
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