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Date:	Thu, 20 Mar 2014 14:12:29 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Chanwoo Choi <cw00.choi@...sung.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 Thursday 20 March 2014 12:26 PM, Chanwoo Choi wrote:
> 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 wrong node->name was given by the extcon provider but the error is being
reported in the consumer.
> 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.

I'm not sure if that log message is helpful in anyway to identify the problem
was because of the wrong node->name.
> 
>>>
>>>
>>>> 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);

dev_name need not be same as node name in all cases.

-Kishon
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