linux-kernel - Re: [PATCH v3 1/2] gpio: designware: switch device node to fwnode

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Date:	Sat, 27 Feb 2016 15:15:40 +0800
From:	Jiang Qiu <qiujiang@...wei.com>
To:	Andy Shevchenko <andy.shevchenko@...il.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	<linuxarm@...wei.com>, <haifeng.wei@...wei.com>,
	<charles.chenxin@...wei.com>
Subject: Re: [PATCH v3 1/2] gpio: designware: switch device node to fwnode

在 2016/2/25 21:43, Andy Shevchenko 写道:
> On Thu, Feb 25, 2016 at 1:58 PM, Jiang Qiu <qiujiang@...wei.com> wrote:
>> 在 2016/2/24 21:46, Andy Shevchenko 写道:
>>> On Wed, Feb 24, 2016 at 2:33 PM, qiujiang <qiujiang@...wei.com> wrote:
> 
>>>  - why do you use fwnode_*() instead of device_property_*() calls?
>>> What prevents us to move to device property API directly?
>> Yes, it looks more reasonable by using devce_property. Howerver,
>> device_get_child_node_count was used here to find each child node. This
>> API output the fwnode_handle for each child node directly, but device
>> property APIs need 'dev' data instead. Actually, the effects of fwnode_*()
>> and device_*() are the same. So, I used fwnode_*() APIs here.
> 
> Right, looks okay then.
> 
>>>> -       node = dev->of_node;
>>>> -       if (!IS_ENABLED(CONFIG_OF_GPIO) || !node)
>>>> +       if (!IS_ENABLED(CONFIG_OF_GPIO) || !(dev->of_node))
>>>>                 return ERR_PTR(-ENODEV);
>>>
>>> So, since you converted to fwnode, do you still need this check?
>>>
>> Although this patch coverted device node to fwnode, only DTs binding was
>> supported here, and patch2 support ACPI will remove this check.
> 
> Yes, but like I said below device_get_child_node_count() will take
> care of that, will it?
Right, device_get_child_node_count() will take of it, this should be removed.
> 
>>>>
>>>> -       nports = of_get_child_count(node);
>>>> +       nports = device_get_child_node_count(dev);
>>>>         if (nports == 0)
>>>>                 return ERR_PTR(-ENODEV);
>>>
>>> ...I think this one fail if it will not found any child.
>> This one fail? yes, it will return to failure.
>> I am not very clear here.
> 
> See above.
Here, device_get_child_node_count will return ZERO if there is not any child.
So, I think this will work ok, will it?
>