On 4 February 2016 at 16:44, Vincent Guittot <vincent.guittot@xxxxxxxxxx> wrote: > On 4 February 2016 at 15:13, Juri Lelli <juri.lelli@xxxxxxx> wrote: >> 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? > > As an example, the uniphier arm64 Soc doesn't have a cpufreq driver so far > >> >> 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? > > AFAICT, They don't have a dedicated cpufreq driver. > > More generally speaking, it can take time before having email sent before the ne d of the sentence ... More generally speaking, it can take time before having a cpufreq driver whereas we want to run and test scheduler behavior of these heterogenous platform Thanks, Vincent > >> >> 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
