Re: [PATCH 04/11] devicetree: bindings: Document qcom,saw2 node

From: Kumar Gala
Date: Tue Nov 05 2013 - 12:16:20 EST



On Nov 1, 2013, at 5:08 PM, Stephen Boyd wrote:

> The saw2 binding describes the SPM/AVS wrapper hardware used to
> control the regulator supplying voltage to the Krait CPUs.
>
> Cc: <devicetree@xxxxxxxxxxxxxxx>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> ---
>
> When a SAW is for a CPU it is put behind the CPU alias region similar
> to the ACC and timers. I haven't documented that here because I'm not using
> it right now. I'm also thinking perhaps l2-saw2 is not important (technically
> its the same hardware block as a CPU's saw). Instead I should point to this
> node via the l2-cache node via some *-supply property. Thoughts?

I don't get this, why wouldn't the SAW just be under the soc node? Do we really need to encode a relationship between the cpu and the SAW?

And kill the "l2-saw2" stuff until its needed.

Also are SAWs specific to a given SoC or not?

>
> .../devicetree/bindings/arm/msm/qcom,saw2.txt | 23 ++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
>
> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
> new file mode 100644
> index 0000000..6360db2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
> @@ -0,0 +1,23 @@
> +* SPM AVS Wrapper 2 (SAW2)
> +
> +The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the
> +Adaptive Voltage Scaling (AVS) hardware. The SPM is programmable
> +micro-controller that transitions a piece of hardware (like a processor) into
> +and out of low power modes via a direct connection to the PMIC. It can also
> +be wired up to interact with other processors in the system, notifying them
> +when a low power state is entered or exited.
> +
> +Required Properties:
> +
> +- compatible : Shall contain "qcom,saw2".
> + A more specific property can be specified as follows:
> + "qcom,l2-saw2"
> +- reg: Specifies the base address and size of the register region.
> +
> +Example:
> +
> + regulator@f9012000 {
> + compatible = "qcom,l2-saw2", "qcom,saw2";
> + reg = <0xf9012000 0x1000>;
> + };
> +
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