Messages in this thread | | | Date | Tue, 4 Aug 2020 12:00:46 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH v2 3/7] arch_topology: disable frequency invariance for CONFIG_BL_SWITCHER |
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On 30-07-20, 12:29, Dietmar Eggemann wrote: > On 30/07/2020 06:24, Viresh Kumar wrote: > > On 22-07-20, 10:37, Ionela Voinescu wrote: > >> +++ b/drivers/base/arch_topology.c > >> @@ -27,6 +27,7 @@ __weak bool arch_freq_counters_available(struct cpumask *cpus) > >> } > >> DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE; > >> > >> +#ifndef CONFIG_BL_SWITCHER > >> void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq, > >> unsigned long max_freq) > >> { > >> @@ -46,6 +47,7 @@ void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq, > >> for_each_cpu(i, cpus) > >> per_cpu(freq_scale, i) = scale; > >> } > >> +#endif > > > > I don't really like this change, the ifdef hackery is disgusting and > > then we are putting that in a completely different part of the kernel. > > > > There are at least these two ways of solving this, maybe more: > > > > - Fix the bl switcher driver and add the complexity in it (which you > > tried to do earlier). > > > > - Add a cpufreq flag to skip arch-set-freq-scale call. > > I agree it's not nice but IMHO the cpufreq flag is worse since we would > introduce new infrastructure only for a deprecated feature. I'm assuming > that BL SWITCHER is the only feature needing this CPUfreq flag extension. > > #ifdef CONFIG_BL_SWITCHER is already in drivers/irqchip/irq-gic.c so > it's ugly already. > > Runtime detecting (via bL_switching_enabled) of BL SWITCHER is right now > also only handled inside vexpress-spc-cpufreq.c via a > bL_switcher_notifier. A mechanism which also sits behind a #ifdef > CONFIG_BL_SWITCHER.
Vexpress one is a driver and so ugliness could be ignored here :)
So here is option number 3 (in continuation of the earlier two options): - Don't do anything for bL switcher, just add a TODO/NOTE in the driver that FIE is broken for switcher. And I don't think anyone will care about FIE for the switcher anyway :)
-- viresh
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