On 04/02/16 13:35, Vincent Guittot wrote: > On 4 February 2016 at 13:16, Juri Lelli <juri.lelli@xxxxxxx> wrote: > > Hi Vincent, > > > > On 04/02/16 13:03, Vincent Guittot wrote: > >> On 4 February 2016 at 10:36, Morten Rasmussen <morten.rasmussen@xxxxxxx> wrote: > >> > On Wed, Feb 03, 2016 at 10:04:37PM +0100, Vincent Guittot wrote: > >> >> On 3 February 2016 at 12:59, Juri Lelli <juri.lelli@xxxxxxx> wrote: > >> > >> [snip] > >> > >> >> > diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile > >> >> > index 9e63fb1..c4025fd 100644 > >> >> > --- a/drivers/cpufreq/Makefile > >> >> > +++ b/drivers/cpufreq/Makefile > >> >> > @@ -1,5 +1,5 @@ > >> >> > # CPUfreq core > >> >> > -obj-$(CONFIG_CPU_FREQ) += cpufreq.o freq_table.o > >> >> > +obj-$(CONFIG_CPU_FREQ) += cpufreq.o freq_table.o cpufreq_capacity.o > >> >> > >> >> Do you really want to have the calibration of capacity dependent of > >> >> cpufreq ? It means that we can't use it without a cpufreq driver. > >> >> IMHO, this creates a unnecessary dependency. I understand that you > >> >> must ensure that core runs at max fequency if a driver is present but > >> >> you should be able to calibrate the capacity if cpufreq is not > >> >> available but you have different capacity because micro architecture > >> > > >> > We could remove the dependency on cpufreq, but it would make things more > >> > complicated for systems which do have frequency scaling as we would have > >> > to either: > >> > > >> > 1) Run the calibration again once cpufreq has been initialized. > >> > >> or wait and let time for a driver to initialize and trig the > >> calibration. If calibration has not been done at the end of the boot, > >> you can force a calibration. If the cpufeq driver is a module and is > >> loaded far later for any good or bad reason, we will have to run the > >> calibration once again but at least the capacity will reflect he > >> current capacity of the CPUs. > >> I'm mainly worried that the compilation of the calibration is > >> dependent of CONFIG_CPU_FREQ not that cpufreq can trig the calibration > >> sequence > >> > > > > Yes, I guess we can make this work in some way. Out of curiosity, > > though, are out there heterogenous platforms that don't use cpufreq? > > At least, you can find several heterogeneous platforms without OPP > table for CPUs in the kernel. That's probably a temporary situation > but which can become a permanent one. It means that we can't calibrate > the CPUs for these platforms. > Sorry, can you make some examples so that I'm sure I understand what you are referring to? Anyway, don't these platform still make use of cpufreq (even if without an OPP table) so that we can still control policy->max and min? Thanks, - Juri -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
