Commit 4ecd31a0 authored Jul 29, 2014 by Stepan Moskovchenko

of: Generate warnings for malformed boolean properties



A properly-formed boolean property does not contain any
value-specific device tree cells. The mere presence of the
name of the property (without a corresponding value)
indicates that a boolean property has been set to 'true'.
However, a common mistake may be to assign a numeric value
to a boolean property, meaning that of_property_read_bool()
will always return 'true' when querying such a property,
even if the property's numeric value has been set to 0.
Therefore, we add a warning that is printed whenever any
user calls of_property_read_bool() on any property that
contains value cells.

Change-Id: I2b626f6f0647ff8c8e8ae729ccea9ede5580e604
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>

parent c57e2816

include/linux/of.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -544,6 +544,16 @@ static inline bool of_property_read_bool(const struct device_node *np,
		{
		struct property *prop = of_find_property(np, propname, NULL);

		/*
		* Boolean properties have no value cells. The "value" of a boolean
		* property is determined by the presence or absence of the property
		* itself, and value cells are disregarded entirely. Declaring a
		* boolean property with a nonzero number of value cells is a common
		* configuration error, since even a boolean property having a value of
		* 0 will be treated as "true" by the DT framework.
		*/
		WARN_ON(prop && prop->length);

		return prop ? true : false;
		}