On Mon, Sep 29, 2014 at 12:53:22PM +0100, Stefan Wahren wrote: > Hi Mark, > > Am 29.09.2014 um 13:09 schrieb Mark Rutland: > > On Sat, Sep 27, 2014 at 01:59:47AM +0100, Stefan Wahren wrote: > >> This patch adds the Device tree bindings for the Freescale MXS > >> on-chip regulators. > >> > >> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx> > >> --- > >> .../bindings/regulator/mxs-regulator.txt | 36 ++++++++++++++++++++ > >> 1 file changed, 36 insertions(+) > >> create mode 100644 Documentation/devicetree/bindings/regulator/mxs-regulator.txt > >> > >> diff --git a/Documentation/devicetree/bindings/regulator/mxs-regulator.txt b/Documentation/devicetree/bindings/regulator/mxs-regulator.txt > >> new file mode 100644 > >> index 0000000..e3133a4 > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/regulator/mxs-regulator.txt > >> @@ -0,0 +1,36 @@ > >> +MXS regulators > >> + > >> +Required node properties: > >> +- compatible: Should be "simple-bus" > > This does not look like an appropriate use of simple-bus. > > > > Why do you want the parent node to be a simple-bus? > > the current parent node in imx28.dtsi looks like a placeholder for the > power sub system: > > power: power@80044000 { > reg = <0x80044000 0x2000>; > status = "disabled"; > }; > > I want to trigger the probing of the child nodes (regulators) without > writing a driver for the complete power sub system. The simple-bus > avoids that. Well, the simple-bus will cause the children to be probed. But it looks like you care about properties of the parent. I don't think that simple-bus is appropriate because it's not being handled as a transparent bridge from the PoV of the children. > > Do we need a extra driver? Perhaps, but it's relatively simple to match on a compatible string and probe children if you just wantto start small for now. > > > >> +- #address-cells: Number of cells required to define regulator register, > >> + must be 1 > >> +- #size-cells: Number of cells required to define register size, must be 1 > > Why must this be the case, given that the child node expects an absolute > > physical address? > > I need a property to define the control register for the regulators > without defining vendor specific properties like "fsl,mxs-control-reg" > or something. You misunderstand me. I was querying the "must be 1" rather than the proeprties themselves. > > > What's wrong with #address-cells = <2>, for example? > > Nothing Then we shouldn't specify "must be 1", no? > > > > >> +- reg: Absolute physical address and size of the register set for the device > > Why is this here _and_ in the child node(s)? > > The parent of the power node is also a simple bus. I use this to > calculate the power status register per offset. > > > What is the difference between this node and its children? > > The parent node represent the power sub system and the regulators are > part of this sub system. > > > Can there be more than one sub-node? > > In the i.MX28 are at least 4 voltage regulators, 1 current regulator and > many more. At first, the driver should implement only 3 voltage > regulators (vddd, vdda, vddio). Ok. I think you need a binding for the power subsystem, and a trivial driver that can match on that and probe the child regulators. Are there components other than voltage or current regulators in the sub system? Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html