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. Thanks, Vincent > I mean, I wouldn't add code and complexity from start, if there are not > good reasons to do so. > > 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
