[PATCH v1 0/2] Introduce devm_of_platform_populate() helper

[PATCH v1 0/2] Introduce devm_of_platform_populate() helper

[Benjamin Gaignard]

Lost of calls to of_platform_populate() are not unbalanced by a call
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. This also could make drivers more robust in case that
probe failed after calling of_platform_populate().

Benjamin Gaignard (2):
  of: add devm_ functions for populate and depopulate
  drm: sti: make driver use devm_of_platform_populate()

 drivers/gpu/drm/sti/sti_drv.c |  3 +-
 drivers/of/platform.c         | 77 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_platform.h   | 20 +++++++++++
 3 files changed, 98 insertions(+), 2 deletions(-)

-- 
1.9.1

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

[Benjamin Gaignard]

Lost of calls to of_platform_populate() are not unbalanced by a call
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.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.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
+ * @lookup: auxdata table for matching id and platform_data with device nodes
+ * @parent: parent to hook devices from, NULL for toplevel
+ *
+ * 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.
+ */
+int devm_of_platform_populate(struct device *dev,
+			      struct device_node *root,
+			      const struct of_device_id *matches,
+			      const struct of_dev_auxdata *lookup,
+			      struct device *parent)
+{
+	struct device **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_of_platform_populate_release,
+			   sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = of_platform_populate(root, matches, lookup, parent);
+	if (ret) {
+		devres_free(ptr);
+	} else {
+		*ptr = parent;
+		devres_add(dev, ptr);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_of_platform_populate);
+
+static int devm_of_platform_match(struct device *dev, void *res, void *data)
+{
+	struct device **ptr = res;
+
+	if (!ptr) {
+		WARN_ON(!ptr);
+		return 0;
+	}
+
+	return *ptr == data;
+}
+
+/**
+ * devm_of_platform_depopulate() - Remove devices populated from device tree
+ * @dev: device that requested to populate from device tree data
+ * @parent: device which children will be removed
+ *
+ * Complementary to devm_of_platform_populate(), this function removes children
+ * of the given device (and, recurrently, their children) that have been
+ * created from their respective device tree nodes (and only those,
+ * leaving others - eg. manually created - unharmed).
+ */
+void devm_of_platform_depopulate(struct device *dev, struct device *parent)
+{
+	int ret;
+
+	ret = devres_release(dev, devm_of_platform_populate_release,
+			     devm_of_platform_match, parent);
+
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL_GPL(devm_of_platform_depopulate);
+
 #ifdef CONFIG_OF_DYNAMIC
 static int of_platform_notify(struct notifier_block *nb,
 				unsigned long action, void *arg)
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index 956a100..282fae3 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -76,6 +76,14 @@ extern int of_platform_default_populate(struct device_node *root,
 					const struct of_dev_auxdata *lookup,
 					struct device *parent);
 extern void of_platform_depopulate(struct device *parent);
+
+extern int devm_of_platform_populate(struct device *dev,
+				     struct device_node *root,
+				     const struct of_device_id *matches,
+				     const struct of_dev_auxdata *lookup,
+				     struct device *parent);
+extern void devm_of_platform_depopulate(struct device *dev,
+					struct device *parent);
 #else
 static inline int of_platform_populate(struct device_node *root,
 					const struct of_device_id *matches,
@@ -91,6 +99,18 @@ static inline int of_platform_default_populate(struct device_node *root,
 	return -ENODEV;
 }
 static inline void of_platform_depopulate(struct device *parent) { }
+
+static inline int devm_of_platform_populate(struct device *dev,
+					    struct device_node *root,
+					    const struct of_device_id *matches,
+					    const struct of_dev_auxdata *lookup,
+					    struct device *parent)
+{
+	return -ENODEV;
+}
+
+static inline void devm_of_platform_depopulate(struct device *dev,
+					       struct device *parent) { }
 #endif
 
 #if defined(CONFIG_OF_DYNAMIC) && defined(CONFIG_OF_ADDRESS)
-- 
1.9.1

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

[Rob Herring]

On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
<benjamin.gaignard@linaro.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.

> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.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.

> + * @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.

> + *
> + * 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.
> + */
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Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

[Benjamin Gaignard]

2017-02-24 15:17 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
> On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
> <benjamin.gaignard@linaro.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@linaro.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.
>> + */
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Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

[Rob Herring]

On Fri, Feb 24, 2017 at 9:13 AM, Benjamin Gaignard
<benjamin.gaignard@linaro.org> wrote:
> 2017-02-24 15:17 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
>> On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
>> <benjamin.gaignard@linaro.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@linaro.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
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Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

[Benjamin Gaignard]

2017-02-24 16:20 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
> On Fri, Feb 24, 2017 at 9:13 AM, Benjamin Gaignard
> <benjamin.gaignard@linaro.org> wrote:
>> 2017-02-24 15:17 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
>>> On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
>>> <benjamin.gaignard@linaro.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@linaro.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.

match parameter is very often set to NULL since this function will
have a limited
scope why not also remove it and only keep dev ?

>
> Rob
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Re: [PATCH v1 1/2] of: add devm_ functions for populate and depopulate

[Rob Herring]

On Fri, Feb 24, 2017 at 9:26 AM, Benjamin Gaignard
<benjamin.gaignard@linaro.org> wrote:
> 2017-02-24 16:20 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
>> On Fri, Feb 24, 2017 at 9:13 AM, Benjamin Gaignard
>> <benjamin.gaignard@linaro.org> wrote:
>>> 2017-02-24 15:17 GMT+01:00 Rob Herring <robh+dt@kernel.org>:
>>>> On Fri, Feb 17, 2017 at 8:31 AM, Benjamin Gaignard
>>>> <benjamin.gaignard@linaro.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@linaro.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.
>
> match parameter is very often set to NULL since this function will
> have a limited
> scope why not also remove it and only keep dev ?

That's fine with me.

Rob
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[PATCH v1 2/2] drm: sti: make driver use devm_of_platform_populate()

[Benjamin Gaignard]

This make sure that of_platform_depopulate() is called if an error
occur in probe after populating the date from the device tree.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
---
 drivers/gpu/drm/sti/sti_drv.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sti/sti_drv.c b/drivers/gpu/drm/sti/sti_drv.c
index ff71e25..01ef9a4 100644
--- a/drivers/gpu/drm/sti/sti_drv.c
+++ b/drivers/gpu/drm/sti/sti_drv.c
@@ -438,7 +438,7 @@ static int sti_platform_probe(struct platform_device *pdev)
 
 	dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
 
-	of_platform_populate(node, NULL, NULL, dev);
+	devm_of_platform_populate(dev, node, NULL, NULL, dev);
 
 	child_np = of_get_next_available_child(node, NULL);
 
@@ -454,7 +454,6 @@ static int sti_platform_probe(struct platform_device *pdev)
 static int sti_platform_remove(struct platform_device *pdev)
 {
 	component_master_del(&pdev->dev, &sti_ops);
-	of_platform_depopulate(&pdev->dev);
 
 	return 0;
 }
-- 
1.9.1

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