Re: [PATCH v6 2/2] Documentation: devicetree: Add boost-frequency binding to list boost mode frequency
From: Mark Rutland <mark.rutland@arm.com>
Date: 2014-05-30 13:08:27
Also in:
linux-arm-kernel, linux-devicetree, linux-samsung-soc
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:
quoted hunk ↗ jump to hunk
From: Thomas Abraham <redacted> Add a new optional boost-frequency binding for specifying the frequencies usable in boost mode. Cc: Rob Herring <robh+dt@kernel.org> Cc: Pawel Moll <redacted> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Ian Campbell <redacted> Cc: Kumar Gala <redacted> Signed-off-by: Thomas Abraham <redacted> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Nishanth Menon <nm@ti.com> Acked-by: Lukasz Majewski <redacted> --- .../devicetree/bindings/cpufreq/cpufreq-boost.txt | 38 ++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-boost.txtdiff --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