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

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Date:   Fri, 24 Feb 2017 16:13:20 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Rob Herring <robh+dt@...nel.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

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)

>
>> + *
>> + * Similar to of_platform_populate(), but will automatically call
>> + * of_platform_depopulate() when the device is unbound from the bus.
>> + *
>> + * Returns 0 on success, < 0 on failure.
>> + */