Re: [PATCH v2 0/4] media: add and use fwnode_graph_for_each_endpoint_scoped()

[Andy Shevchenko]

On Wed, Jun 24, 2026 at 03:46:48PM -0500, Frank Li wrote:
> On Wed, Jun 24, 2026 at 11:02:37PM +0300, Laurent Pinchart wrote:
> > On Wed, Jun 24, 2026 at 02:35:14PM -0500, Frank Li wrote:
> > > On Wed, Jun 24, 2026 at 10:19:35PM +0300, Laurent Pinchart wrote:
> > > > On Wed, Jun 24, 2026 at 01:00:08PM -0400, Frank.Li@xxxxxxxxxxx wrote:
> > > > > Add new helper macro fwnode_graph_for_each_endpoint_scoped() and use it
> > > > > simplify media code.
> > > > >
> > > > > Typical example should qualcomm's driver (camss.c), the v4l2_mc.c and
> > > > > rkisp1-dev.c only silience improvement.
> > > > >
> > > > > Anyways, *_for_each_*_scoped() already use widely and make code clean.
> > > > >
> > > > > Build test only.
> > > > >
> > > > > Sakari Ailus:
> > > > > 	when I try to improve the patch
> > > > > "Add common helper library for 1-to-1 subdev registration", I found need
> > > > > camss.c pattern, so I create this small improvement firstly.
> > > >
> > > > Those are nice cleanups, thank you.
> > > >
> > > > After applying this series, the only left users of the
> > > > fwnode_graph_for_each_endpoint() macro are in drivers/base/property.c.
> > >
> > > I already checked previously, two place use it.
> > >
> > > fwnode_graph_get_endpoint_count(), it will go though all endpoints, last
> > > ep is NULL, which totally equial to scoped() version.
> > >
> > > another one fwnode_graph_get_endpoint_by_id(), which return ep, expect
> > > caller to call put().
> > >
> > > if use scoped() version, need use no_free_ptr() at return, which make think
> > > a little bit complex.
> >
> > It would introduce a tiny bit of extra complexity there, but the
> > advantage (in my opinion) is that we'll be able to remove the less safe
> > fwnode_graph_for_each_endpoint() macro.
> >
> > Now one may argue that the risk of
> > fwnode_graph_for_each_endpoint_scoped() is returning the iterator
> > without using no_free_ptr(). I wonder if that would be easier to catch
> > in static analysis tools than the current pattern that leaks a reference
> > when exiting the loop early.
> 
> It's not big deal, if everyone prefer drop fwnode_graph_for_each_endpoint(),
> I can do it.

I slightly tend to the safest option (see below), but as a compromise I can
suggest to inline the fwnode_graph_for_each_endpoint() into that single user
that doesn't need a put. However, this may uglify the code and rise a question
of the consistency. So, consider that suggestion with grain of salt and apply
only if we have wider agreement with it.

> > > It'd better leave these as it.

TL;DR:
This is the safest option, of course. And as mentioned above I slightly
prefer this way. Another argument is that in some cases we might want to
have it in the future and since we have an existing user, let it live.

-- 
With Best Regards,
Andy Shevchenko