Re: [net-next PATCH v3 09/15] device property: Introduce fwnode_get_id()

From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Saravana Kannan <saravanak@google.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Calvin Johnson <calvin.johnson@oss.nxp.com>,
	Grant Likely <grant.likely@arm.com>,
	Jeremy Linton <jeremy.linton@arm.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	Cristi Sovaiala <cristian.sovaiala@nxp.com>,
	Florin Laurentiu Chiculita <florinlaurentiu.chiculita@nxp.com>,
	Ioana Ciornei <ioana.ciornei@nxp.com>,
	Madalin Bucur <madalin.bucur@oss.nxp.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Marcin Wojtas <mw@semihalf.com>,
	Pieter Jansen Van Vuuren <pieter.jansenvv@bamboosystems.io>,
	Jon <jon@solid-run.com>,
	Diana Madalina Craciun <diana.craciun@nxp.com>,
	LKML <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Laurentiu Tudor <laurentiu.tudor@nxp.com>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	"linux.cj" <linux.cj@gmail.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
	Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [net-next PATCH v3 09/15] device property: Introduce fwnode_get_id()
Date: Fri, 22 Jan 2021 17:34:12 +0100	[thread overview]
Message-ID: <CAJZ5v0gUCUxJX9sGJiZ+zTVYrc3rjuUO2B2fx+O6PewbG7F8aw@mail.gmail.com> (raw)
In-Reply-To: <CAGETcx8DP8J53ntxX2VCSnbMfq1qki7gD-md+NC_jVfOkTam3g@mail.gmail.com>

On Wed, Jan 20, 2021 at 9:01 PM Saravana Kannan <saravanak@google.com> wrote:
>
> On Wed, Jan 20, 2021 at 11:15 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
> >
> > On Wed, Jan 20, 2021 at 7:51 PM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:
> > >
> > > On Wed, Jan 20, 2021 at 8:18 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> > > > On Tue, Jan 12, 2021 at 7:02 PM Andy Shevchenko
> > > > <andy.shevchenko@gmail.com> wrote:
> > > > > On Tue, Jan 12, 2021 at 09:30:31AM -0800, Saravana Kannan wrote:
> > > > > > On Tue, Jan 12, 2021 at 5:42 AM Calvin Johnson
> > > > > > <calvin.johnson@oss.nxp.com> wrote:
> > >
> > > ...
> > >
> > > > > > > +       ret = fwnode_property_read_u32(fwnode, "reg", id);
> > > > > > > +       if (!(ret && is_acpi_node(fwnode)))
> > > > > > > +               return ret;
> > > > > > > +
> > > > > > > +#ifdef CONFIG_ACPI
> > > > > > > +       status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode),
> > > > > > > +                                      METHOD_NAME__ADR, NULL, &adr);
> > > > > > > +       if (ACPI_FAILURE(status))
> > > > > > > +               return -EINVAL;
> > > > > > > +       *id = (u32)adr;
> > > > > > > +#endif
> > > > > > > +       return 0;
> > >
> > > > > > Also ACPI and DT
> > > > > > aren't mutually exclusive if I'm not mistaken.
> > > > >
> > > > > That's why we try 'reg' property for both cases first.
> > > > >
> > > > > is_acpi_fwnode() conditional is that what I don't like though.
> > > >
> > > > I'm not sure what you mean here, care to elaborate?
> > >
> > > I meant is_acpi_node(fwnode) in the conditional.
> > >
> > > I think it's redundant and we can simple do something like this:
> > >
> > >   if (ret) {
> > > #ifdef ACPI
> > >     ...
> > > #else
> > >     return ret;
> > > #endif
> > >   }
> > >   return 0;
> > >
> > > --
> >
> > Right, that should work.  And I'd prefer it too.
>
> Rafael,
>
> I'd rather this new function be an ops instead of a bunch of #ifdef or
> if (acpi) checks. Thoughts?

Well, it looks more like a helper function than like an op and I'm not
even sure how many potential users of it will expect that _ADR should
be evaluated in the absence of the "reg" property.

It's just that the "reg" property happens to be kind of an _ADR
equivalent in this particular binding AFAICS.