Re: [PATCH v2] media: i2c: thp7312: use fwnode_for_each_child_node()

[Matti Vaittinen]

On 08/04/2025 13:36, Sakari Ailus wrote:
> Hei Laurent, Matti,
>
> On Tue, Apr 08, 2025 at 01:26:42PM +0300, Matti Vaittinen wrote:
> > On 08/04/2025 13:12, Laurent Pinchart wrote:
> > > Hi Sakari,
> > >
> > > On Tue, Apr 08, 2025 at 08:48:45AM +0000, Sakari Ailus wrote:
> > > > On Fri, Mar 21, 2025 at 12:41:00PM +0200, Laurent Pinchart wrote:
> > > > > On Fri, Mar 21, 2025 at 10:58:27AM +0200, Matti Vaittinen wrote:
> > > > > > When fwnode_for_each_available_child_node() is used on the device-tree
> > > > > > backed systems, it renders to same operation as the
> > > > > > fwnode_for_each_child_node(), because the fwnode_for_each_child_node()
> > > > > > does only iterate through those device-tree nodes which are available.
> > > > >
> > > > > This makes me wonder why the OF backend implements
> > > > > fwnode_for_each_child_node() as fwnode_for_each_available_child_node().
> > > > > Is that on purpose, or is it a bug ?
> > > >
> > > > I discussed this with Rafael and he didn't recall why the original
> > > > implementation was like that. The general direction later on has been not
> > > > to present unavailable nodes over the fwnode interface.
> > > >
> > > > So I'd say:
> > > >
> > > > Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > >
> > > > We should also change the documentation of the fwnode API accordingly.
> > >
> > > Does that also mean that the fwnode_for_each_available_child_node()
> > > function will be dropped ? It's used by few drivers (5 in addition to
> > > the thp7312 driver, plus 3 call sites in drivers/base/core.c), so a
> > > patch series to drop it should be easy.
> >
> > I assume the fwnode_for_each_available_child_node() still makes sense for
> > ACPI backed users, no?
>
> Not really (see my earlier explanation in
> <Z9mQPJwnKAkPHriT@kekkonen.localdomain>).

I capture that the _named_ available nodes don't have value as ACPI 
names aren't really what is expected by the _named_ callers. What I 
didn't pick is that the fwnode_for_each_available_child_node() - which 
should iterate all available child nodes ignoring the name - wouldn't be 
useful.

> I think all the *available* stuff
> should be removed from include/linux/property.h, apart from
> fwnode_device_is_availble(), which should be turned to work on struct
> device to signal its availability for device nodes only.

I am not saying I have any understanding of the uses of the 
'unavailable' nodes. As such I am not arguing over what you say here :)

Yours,
	-- Matti