On Fri, 9 Mar 2012 11:04:35 +0100, Jean-Christophe PLAGNIOL-VILLARD
<plagn...@jcrosoft.com> wrote:
> On 18:44 Thu 08 Mar , Grant Likely wrote:
> > On Tue, 7 Feb 2012 05:13:48 +0100, Jean-Christophe PLAGNIOL-VILLARD
> > <plagn...@jcrosoft.com> wrote:
> > > of_property_read_bool
> > >
> > > Search for a property in a device node and read a 32-bit value from
> > > it. Returns 0 if <0> or if the property does not exist, 1 if <1> or none.
> > >
> > > this will allow to disable a boolean
> > >
> > > is-ok; => true
> > > is-ok = <1>; => true
> > > is-ok = <0>; => false
> > >
> > > Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagn...@jcrosoft.com>
> > > Cc: devicetree-discuss@lists.ozlabs.org
> > > ---
> > > Hi,
> > >
> > > if this is ok I'll rebase my mtd and i2c patch to use it
> > >
> > > Best Regards,
> > > J.
> > > drivers/of/base.c | 30 ++++++++++++++++++++++++++++++
> > > include/linux/of.h | 8 ++++++++
> > > 2 files changed, 38 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > > index 133908a..a0eaf08 100644
> > > --- a/drivers/of/base.c
> > > +++ b/drivers/of/base.c
> > > @@ -686,6 +686,36 @@ int of_property_read_u64(const struct device_node
> > > *np, const char *propname,
> > > EXPORT_SYMBOL_GPL(of_property_read_u64);
> > >
> > > /**
> > > + * of_property_read_bool - Find and read a boolean from a property
> > > + * @np: device node from which the property value is to be read.
> > > + * @propname: name of the property to be searched.
> > > + *
> > > + * Search for a property in a device node and read a 32-bit value from
> > > + * it. Returns 0 if <0> or if the property does not exist, 1 if <1> or
> > > none.
> > > + *
> > > + * is-ok; => true
> > > + * is-ok = <1>; => true
> > > + * is-ok = <0>; => false
> > > + */
> > > +int of_property_read_bool(const struct device_node *np, const char
> > > *propname)
> > > +{
> > > + u32 reg;
> > > + int ret = of_property_read_u32(np, propname, ®);
> > > +
> > > + 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.
g.
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