linux-kernel - Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

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Date:   Fri, 24 Feb 2017 09:20:17 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Benjamin Gaignard <benjamin.gaignard@...aro.org>
Cc:     Frank Rowand <frowand.list@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Vincent Abriou <vincent.abriou@...com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        "linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

On Fri, Feb 24, 2017 at 9:13 AM, Benjamin Gaignard
<benjamin.gaignard@...aro.org> wrote:
> 2017-02-24 15:17 GMT+01:00 Rob Herring <robh+dt@...nel.org>:
>> On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
>> <benjamin.gaignard@...aro.org> wrote:
>>> Lost of calls to of_platform_populate() are not unbalanced by a call
>>
>> s/Lost/Lots/
>>
>>> to of_platform_depopulate(). This create issues while drivers are
>>> bind/unbind.
>>>
>>> In way to solve those issues is to add devm_of_platform_populate()
>>> which will call of_platform_depopulate() when the device is unbound
>>> from the bus.
>>
>> One complication is of_platform_populate is designed to be called
>> multiple times. We call it with the default match table and then
>> platforms can call it again with a custom match table for example.
>
> I do not plan to use it every where but only in some drivers probe()
> to avoid adding goto to call of_platform_depopulate() for each error
> cases which may occur after calling populate.
>
>>
>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...aro.org>
>>> ---
>>>  drivers/of/platform.c       | 77 +++++++++++++++++++++++++++++++++++++++++++++
>>>  include/linux/of_platform.h | 20 ++++++++++++
>>>  2 files changed, 97 insertions(+)
>>>
>>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>>> index b8064bc..3dbebf7 100644
>>> --- a/drivers/of/platform.c
>>> +++ b/drivers/of/platform.c
>>> @@ -571,6 +571,83 @@ void of_platform_depopulate(struct device *parent)
>>>  }
>>>  EXPORT_SYMBOL_GPL(of_platform_depopulate);
>>>
>>> +static void devm_of_platform_populate_release(struct device *dev, void *res)
>>> +{
>>> +       of_platform_depopulate(*(struct device **)res);
>>> +}
>>> +
>>> +/**
>>> + * devm_of_platform_populate() - Populate platform_devices from device tree data
>>> + * @dev: device that requested to populate from device tree data
>>> + * @root: parent of the first level to probe or NULL for the root of the tree
>>> + * @matches: match table, NULL to use the default
>>
>> NULL is no match table, not the default which means only populate
>> immediate children.
>
> I have copy of_platform_populate() description...
> I replace it by: @matches: match table (could be NULL)
>
>>
>>> + * @lookup: auxdata table for matching id and platform_data with device nodes
>>> + * @parent: parent to hook devices from, NULL for toplevel
>>
>> I think this needs to be a bit different args as the use is limited.
>> root and parent must not be NULL. dev should be the same as parent.
>> lookup was for legacy, so drop that.
>
> So function prototype will become:
> int devm_of_platform_populate(struct device *dev, struct device_node
> *root, const struct of_device_id *matches)

I just noticed something else too. dev->of_node should equal root I
think, so we can get rid of root param.

Rob