`On Mon, Jan 28, 2019 at 04:55:21PM +0000, Quentin Perret wrote:> From: Dietmar Eggemann <dietmar.eggemann@arm.com>>> A CPUfreq driver, like the scpi driver used on Juno boards, which> provide the Energy Model with power cost information via the PM_OPP> of_dev_pm_opp_get_cpu_power() function, do need the> dynamic-power-coefficient (C) in the device tree.>> Method used to obtain the C value:> C is computed by measuring energy (E) consumption of a frequency domain> (FD) over a 10s runtime (t) sysbench workload running at each Operating> Performance Point (OPP) affine to 1 or 2 CPUs of that FD while the other> CPUs of the system are hotplugged out.> By definition all CPUs of a FD have the the same micro-architecture. An> OPP is characterized by a certain frequency (f) and voltage (V) value.> The corresponding power values (P) are calculated by dividing the delta> of the E values between the runs with 2 and 1 CPUs by t.>> With n data tuples (P, f, V), n equal to number of OPPs for this> frequency domain, we can solve C by:>> P = Pstat + Pdyn>> P = Pstat + CV²f>> Cx = (Px - P1)/(Vx²fx - V1²f1) with x = {2, ..., n}>> The C value is the arithmetic mean out of {C2, ..., Cn}.>> Since DVFS is broken on Juno r1, no dynamic-power-coefficient> information has been added to its dts file.>Since the binding for "dynamic-power-coefficient" property already exist,and I don't see any dependency for this and the next patch(TC2) on thisseries, I will apply them. Please shout if for any reason that's not true.--Regards,Sudeep`