On 11/10/2024 07:39, Sakari Ailus wrote:
> Hi Javier,
>
> On Tue, Oct 08, 2024 at 06:10:27PM +0200, Javier Carrasco wrote:
>> Introduce the scoped variant of the
>> fwnode_for_each_available_child_node() to automatically decrement the
>> child's refcount when it goes out of scope, removing the need for
>> explicit calls to fwnode_handle_put().
>>
>> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@xxxxxxxxx>
>> ---
>> include/linux/property.h | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/include/linux/property.h b/include/linux/property.h
>> index 61fc20e5f81f..b37508ecf606 100644
>> --- a/include/linux/property.h
>> +++ b/include/linux/property.h
>> @@ -168,6 +168,11 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
>> for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
>> child = fwnode_get_next_available_child_node(fwnode, child))
>>
>> +#define fwnode_for_each_available_child_node_scoped(fwnode, child) \
>> + for (struct fwnode_handle *child __free(fwnode_handle) = \
>> + fwnode_get_next_available_child_node(fwnode, NULL); child; \
>> + child = fwnode_get_next_available_child_node(fwnode, child))
>> +
>
> On OF, the implementation of the .get_next_child_node() fwnode op is:
>
> static struct fwnode_handle *
> of_fwnode_get_next_child_node(const struct fwnode_handle *fwnode,
> struct fwnode_handle *child)
> {
> return of_fwnode_handle(of_get_next_available_child(to_of_node(fwnode),
> to_of_node(child)));
> }
>
> On ACPI we currently have .device_is_available() returning false but that
> probably should be returning true instead (it's been virtually unused
> previously).
>
> That makes fwnode_get_next_available_child_node() and
> fwnode_get_next_child_node() equivalent on both ACPI and OF. Presumably
> creating unavailable nodes would be useless on swnode, too.
>
> So my question is: what do we gain by adding all these fwnode_*available()
> helpers?
>
>> struct fwnode_handle *device_get_next_child_node(const struct device *dev,
>> struct fwnode_handle *child);
>
Hi Sakari, thanks for your feedback.
I thought that the difference is not in OF (which either way ends up
calling __of_device_is_available()), but in ACPI.
For fwnode_for_each_child_node(), the ACPI callback is
acpi_get_next_subnode(), and I don't see that the device_is_available()
callback is used in that case.
For fwnode_for_each_available_child_node(),
fwnode_get_next_available_child_node() is used, which checks
fwnode_device_is_available(), which then calls device_is_available().
What's the catch?
Thanks again and best regards,
Javier Carrasco
