linux-kernel - Re: [PATCH v1 2/6] device property: Add fwnode_property_match_property

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Message-ID: <CAJZ5v0gOXsX98jQTRSwoYmfYBfva1RHTsDaLL++m7c+kLjStVA@mail.gmail.com>
Date:   Tue, 17 Oct 2023 21:19:30 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Antoniu Miclaus <antoniu.miclaus@...log.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Gerald Loacker <gerald.loacker@...fvision.net>,
        Gwendal Grignou <gwendal@...omium.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>
Subject: Re: [PATCH v1 2/6] device property: Add fwnode_property_match_property_string()

On Mon, Aug 28, 2023 at 8:00 PM Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Thu, 10 Aug 2023 16:26:54 +0300
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
>
> > On Wed, Aug 09, 2023 at 06:59:44PM +0100, Jonathan Cameron wrote:
> > > On Tue,  8 Aug 2023 19:27:56 +0300
> > > Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> >
> > ...
> >
> > > > +int fwnode_property_match_property_string(const struct fwnode_handle *fwnode,
> > > > + const char *propname, const char * const *array, size_t n)
> > >
> > > Hi Andy,
> > >
> > > Whilst I'm not 100% sold on adding ever increasing complexity to what we
> > > match, this one feels like a common enough thing to be worth providing.
> >
> > Yep, that's why I considered it's good to add (and because of new comers).
> >
> > > Looking at the usecases I wonder if it would be better to pass in
> > > an unsigned int *ret which is only updated on a match?
> >
> > So the question is here are we going to match (pun intended) the prototype to
> > the device_property_match*() family of functions or to device_property_read_*()
> > one. If the latter, this has to be renamed, but then it probably will contradict
> > the semantics as we are _matching_ against something and not just _reading_
> > something.
> >
> > That said, do you agree that current implementation is (slightly) better from
> > these aspects? Anyway, look at the below.
> >
> > > That way the common properties approach of not checking the return value
> > > if we have an optional property would apply.
> > >
> > > e.g. patch 3
> >
> > Only?
> I didn't look further :)
>
> >
> > > would end up with a block that looks like:
> > >
> > >     st->input_mode = ADMV1014_IQ_MODE;
> > >     device_property_match_property_string(&spi->dev, "adi,input-mode",
> > >                                           input_mode_names,
> > >                                           ARRAY_SIZE(input_mode_names),
> > >                                           &st->input_mode);
> > >
> > > Only neat and tidy if the thing being optionally read into is an unsigned int
> > > though (otherwise you still need a local variable)
> >
> > We also can have a hybrid variant, returning in both sides
> >
> >   int device_property_match_property_string(..., size_t *index)
> >   {
> >         if (index)
> >                 *index = ret;
> >         return ret;
> >   }
> >
> > (also note the correct return type as it has to match to @n).
> >
> > Would it be still okay or too over engineered?
> >
> Probably over engineered....
>
> Lets stick to what you have.  If various firmware folk are happy with
> the new function that's fine by me.  Rafael?

Sorry for the delay, I've lost track of this.

Honestly, I have no strong opinion, but I think that this is going to
reduce some code duplication which is a valid purpose, so please feel
free to add

Acked-by: Rafael J. Wysocki <rafael@...nel.org>

to this patch.

Thanks!