On 27/11/2018 04:57, Viresh Kumar wrote: > On 26-11-18, 13:20, Daniel Lezcano wrote: >> diff --git a/Documentation/devicetree/bindings/arm/cpu-capacity.txt b/Documentation/devicetree/bindings/arm/cpu-capacity.txt >> index 84262cd..f53a3c9 100644 >> --- a/Documentation/devicetree/bindings/arm/cpu-capacity.txt >> +++ b/Documentation/devicetree/bindings/arm/cpu-capacity.txt >> @@ -54,6 +54,12 @@ fall back to the default capacity value for every CPU. If cpufreq is not >> available, final capacities are calculated by directly using capacity-dmips- >> mhz values (normalized w.r.t. the highest value found while parsing the DT). >> >> +If capacity-dmips-mhz is not specified or if the parsing fails, the >> +default capacity value will be computed against the highest frequency. >> +When all CPUs have the same OPP, they will have the same capacity >> +value otherwise the capacity will be scaled down for CPUs having lower >> +frequencies. > > I know you added this based on Quentin's feedback, but I wonder if this is > really required and if it is improving anything at all. This is what the > documentation says currently without this patch: > > " > capacity-dmips-mhz is an optional cpu node [1] property: u32 value > representing CPU capacity expressed in normalized DMIPS/MHz. At boot time, the > maximum frequency available to the cpu is then used to calculate the capacity > value internally used by the kernel. > > capacity-dmips-mhz property is all-or-nothing: if it is specified for a cpu > node, it has to be specified for every other cpu nodes, or the system will > fall back to the default capacity value for every CPU. If cpufreq is not > available, final capacities are calculated by directly using capacity-dmips- > mhz values (normalized w.r.t. the highest value found while parsing the DT). > " > > So it already clearly says two things: > - If all CPUs don't have this property, we fallback to default capacity for > every CPU. > - And the OS may also normalize the capacity based on the maximum frequency. > > What more do we want to add here ? I think what is new is the silver-gold platform. I agree the description above gives us the information but in a condensed way. With this extra paragraph we elaborate a bit and make it more clear for SMP/AMP systems. -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
