Subject: Re: [PATCH 04/10] regulator: of: switch to using class_find_device_by_fwnode()

From: Dmitry Torokhov <[email-masked]>
Date: Mon, 23 Mar 2026 15:48:42 -0700

On Mon, Mar 23, 2026 at 11:39:03PM +0100, Andrew Lunn wrote:
> > If there is a deprecated property you can do:
> > 
> > 	error = device_property_read_u32(dev, "prop", &val);
> > 	if (error == -ENOENT)
> > 		error = device_property_read_u32(dev, "deprecated-prop", &val);
> 
> It is not as simple as that. There are a lot of optional
> properties. Say "prop" is optional? And not present. So -ENOENT. We
> then look for this deprecated property. That should not happen.

Why? That is exactly what you want: you favor new one if it is present
and fall back to deprecated one if it is absent. And then you decide
whether to continue or abort.

Or you are saying that new property is optional but old one was
mandatory? Not sure...

> 
> Using of_property_read_u32(np, "deprecated-prop", &val) actually makes
> it stand out, it is special somehow, which is good, because it is
> special.

If you only have of_property_read_u32() then it will not stand out. If
you advocate of using device_property_read_u32() normally but
of_property_read_u32() for deprecated only - that is a possibility, but
I do not know if anyone does this.

Thanks.

-- 
Dmitry