Re: [PATCH V2 3/3] ARM: dts: db8500: add node property "regulator-compatible" regulator node

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On 19/06/12 18:32, Stephen Warren wrote:
On 06/19/2012 10:13 AM, Lee Jones wrote:
>  On 19/06/12 15:28, Laxman Dewangan wrote:
>>  Device's regulator matches their hardware counterparts with the
>>  property "regulator-compatible" of each child regulator node in
>>  place of the child node.
>>  Add the property "regulator-compatible" for each regulator with
>>  their name.
>>
>>  Signed-off-by: Laxman Dewangan<ldewangan@xxxxxxxxxx>
>>  ---
>>  Changes from V1:
>>     - This is new change in V2.
>>
>>     arch/arm/boot/dts/db8500.dtsi |  128
>>  +++++++++++++++++++++++++++++++----------
>>     1 files changed, 97 insertions(+), 31 deletions(-)
>>
>>  diff --git a/arch/arm/boot/dts/db8500.dtsi
>>  b/arch/arm/boot/dts/db8500.dtsi
>>  index 4ad5160..9548f80 100644
>>  --- a/arch/arm/boot/dts/db8500.dtsi
>>  +++ b/arch/arm/boot/dts/db8500.dtsi
>>  @@ -203,107 +203,149 @@
>>
>>                 db8500-prcmu-regulators {
>>                     compatible = "stericsson,db8500-prcmu-regulator";
>>  +                #address-cells =<1>;
>>  +                #size-cells =<0>;
>
>  Why are these and the reg properties required?
DT nodes should be named after the type of object they describe (e.g.
"regulator") rather than the name of the object they're describing (e.g.
"vape").

Once you've made that change, you end up with many nodes with the same
name in the same parent, so you need to make their names unique. You do
this by adding a "unit address" to each of them - "@0", "@1", ... But,
in order to be "allowed" to use such a unit address, you need a reg
property that matches the unit address, and #address-cells/#size-cells
in the parent node.

I don't like it. By doing this you are preventing any regulator from being registered by of_platform_populate(). Also, the nodes are already placed under an identifying node "db8500-prcmu-regulators", so we know they are regulators, making the regulator@x, the reg property and the *-cells properties unnecessary cruft.

I'd prefer to have the second label removed and just to call the regulators by their correct name. The property names become functionally redundant after the previous patch has been applied in any case.

Something like this:

 			db8500-prcmu-regulators {
 				compatible = "stericsson,db8500-prcmu-regulator";

 				// DB8500_REGULATOR_VAPE
-				db8500_vape_reg: db8500_vape {
+				db8500_vape {
+					regulator-compatible = "db8500_vape";
 					regulator-name = "db8500-vape";
 					regulator-always-on;
 				};

It's also a shame we can't do anything about the regulator-name, or regulator-compatible property naming conventions. They are almost always going to be either extremely similar or even the same. Seems like a bit of a wasted property to me at this point.

--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
M: +44 77 88 633 515
Linaro.org │ Open source software for ARM SoCs
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