linux-kernel - Re: [PATCH v5 09/12] Driver core: Unified interface for firmware node properties

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Message-ID: <2472256.PcjMGW56U7@wuerfel>
Date:	Mon, 20 Oct 2014 16:14:35 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Aaron Lu <aaron.lu@...el.com>, devicetree@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Bryan Wu <cooloney@...il.com>,
	Darren Hart <dvhart@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v5 09/12] Driver core: Unified interface for firmware node properties

On Monday 20 October 2014 01:30:47 Rafael J. Wysocki wrote:
> On Saturday, October 18, 2014 11:35:21 AM Arnd Bergmann wrote:
> > On Friday 17 October 2014 14:14:53 Rafael J. Wysocki wrote:
> > > +/**
> > > + * fwnode_property_present - check if a property of a firmware node is present
> > > + * @fwnode: Firmware node whose property to check
> > > + * @propname: Name of the property
> > > + */
> > > +bool fwnode_property_present(struct fwnode_handle *fwnode, const char *propname)
> > > +{
> > > +       if (is_of_node(fwnode))
> > > +               return of_property_read_bool(of_node(fwnode), propname);
> > > +       else if (is_acpi_node(fwnode))
> > > +               return !acpi_dev_prop_get(acpi_node(fwnode), propname, NULL);
> > > +
> > > +       return false;
> > > +}
> > > +EXPORT_SYMBOL_GPL(fwnode_property_present);
> > > 
> > 
> > Should this be
> > 
> >               return acpi_dev_prop_get(acpi_node(fwnode), propname, NULL);
> > 
> > without the '!'?
> 
> No, acpi_dev_prop_get() returns 0 on success. 

Ah, got it now.

> > I'm also unsure about the '_present' vs '_read_bool' naming. IIRC we had
> > a long debate about this before we decided on 'read_bool' for DT, and
> > I don't really want to start a new debate, but being consistent would
> > be nice.
> > 
> > We could of course have
> > 
> > static inline bool fwnode_property_read_bool(struct fwnode_handle *fwnode, const char *propname)
> > {
> >       return fwnode_property_present(fwnode, propname);
> > }
> > 
> > which is completely redundant, but would help for drivers using the
> > interface to document whether we are checking for bool property that
> > we expect to be either empty or absent (_get_bool), vs checking for
> > the presence of a non-empty property (_present).
> 
> I'm fine with that, so I'll add fwnode_property_read_bool() (and an analogous
> wrapper for device_) to patches [02/12] and [09/12].
> 
> I'll be sending updates of them shortly, so please have a look at those.

Ok, will do.

	Arnd
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