Hi,
Apologies for being somewhat late w.r.t. review on this.
On Fri, May 30, 2014 at 10:01:17AM +0100, Thomas Abraham wrote:
> From: Thomas Abraham <thomas.ab@xxxxxxxxxxx>
>
> Add a new optional boost-frequency binding for specifying the frequencies
> usable in boost mode.
>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Pawel Moll <pawel.moll@xxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Ian Campbell <ijc+devicetree@xxxxxxxxxxxxxx>
> Cc: Kumar Gala <galak@xxxxxxxxxxxxxx>
> Signed-off-by: Thomas Abraham <thomas.ab@xxxxxxxxxxx>
> Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Acked-by: Nishanth Menon <nm@xxxxxx>
> Acked-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx>
> ---
> .../devicetree/bindings/cpufreq/cpufreq-boost.txt | 38 ++++++++++++++++++++
> 1 file changed, 38 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-boost.txt
>
> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-boost.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-boost.txt
> new file mode 100644
> index 0000000..63ed0fc
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-boost.txt
> @@ -0,0 +1,38 @@
> +* Device tree binding for CPU boost frequency (aka over-clocking)
> +
> +Certain CPU's can be operated in optional 'boost' mode (or sometimes referred as
Nit: CPUs (we're not greengrocers [1])
> +overclocking) in which the CPU can operate at frequencies which are not
> +specified by the manufacturer as CPU's operating frequency.
> +
> +Optional Properties:
> +- boost-frequencies: list of frequencies in KHz to be used only in boost mode.
> + This list should be a subset of frequencies listed in "operating-points"
> + property. Refer to Documentation/devicetree/bindings/power/opp.txt for
> + details about "operating-points" property.
What is 'boost-mode'?
What are the limitations on boost frequencies? When is a CPU expected to
go to these frequencies and for now long? When should I as a dt author
place elements in boost-frequencies?
Why are these in both operating-points and boost-frequencies? It'll be
really easy to accidentally forget to mark something as a
boost-frequency this way. Why not have a boost-points instead?
> +
> +Example:
> +
> + cpus {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + cpu@0 {
> + device_type = "cpu";
> + compatible = "arm,cortex-a9";
> + reg = <0>;
> +
> + operating-points = <
> + 1500000 1350000
> + 1400000 1287500
> + 1300000 1250000
> + 1200000 1187500
> + 1100000 1137500
> + 1000000 1087500
> + >;
> + boost-frequencies = <1500000 1400000>;
This is more of a general issue, but I hate the whole cpufreq-cpu0 way
of assuming that all CPUs mirror CPU0.
It would be nicer if either this were dropped in /cpus or repeated
per-cpu.
Cheers,
Mark.
> + };
> + cpu@1 {
> + device_type = "cpu";
> + compatible = "arm,cortex-a9";
> + reg = <1>;
> + };
> + };
> --
> 1.7.9.5
>
>
[1] http://en.wikipedia.org/wiki/Apostrophe#Superfluous_apostrophes_.28.22greengrocers.27_apostrophes.22.29
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