From mboxrd@z Thu Jan  1 00:00:00 1970
From: plagnioj@jcrosoft.com (Jean-Christophe PLAGNIOL-VILLARD)
Date: Fri, 9 Mar 2012 17:36:08 +0100
Subject: [PATCH 1/1] of: introduce helper to manage boolean
In-Reply-To: <20120309162638.92E813E0880@localhost>
References: <1328588028-24766-1-git-send-email-plagnioj@jcrosoft.com>
 <20120309014441.8236B3E0903@localhost>
 <20120309100435.GN27213@game.jcrosoft.org>
 <20120309162638.92E813E0880@localhost>
Message-ID: <20120309163608.GQ27213@game.jcrosoft.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

> > > > +int of_property_read_bool(const struct device_node *np, const char *propname)
> > > > +{
> > > > +	u32 reg;
> > > > +	int ret = of_property_read_u32(np, propname, &reg);
> > > > +
> > > > +	switch (ret) {
> > > > +	case -EINVAL:
> > > > +		return false;
> > > > +	case -ENODATA:
> > > > +		return true;
> > > > +	case 0:
> > > > +		return reg == 1;
> > > 
> > > Ugh.  so any value other than 1 returns false?  I think that will surprise
> > > most people.
> > > 
> > > I don't like this api or binding.  If it is a bool property, then why isn't
> > > simply testing for the property existance sufficient?
> > no if you want to disable it
> > 
> > if a bool is define in the dtsi and want to disable it int the dts
> > 
> > if you we can do the the invert
> > 
> > if !0 => true
> > 
> > is-ok;			=> true
> > is-ok = <val != 0>;	=> true
> > is-ok = <0>;		=> false
> 
> This is a failure of the dtc tool, not the binding.  Accepting this binding
> means we have to live with it for a very long time.  It needs to be fixed
> in dtc instead so that properties can be deleted instead of only modified.
I understand your idea but today if you put and value in the property it's true.

So is-ok = <0>; is true also which is illogical as in any language a boolean is
true (1) or false (0). When I read the property I will understand false not true

And I see no good way to add the "delete" in dtc.

Best Regards,
J.