Messages in this thread |  | | Date | Thu, 9 Jul 2020 14:39:12 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH 1/8] cpufreq: allow drivers to flag custom support for freq invariance |
| |
On 09-07-20, 09:53, Ionela Voinescu wrote: > On Monday 06 Jul 2020 at 14:14:47 (+0200), Dietmar Eggemann wrote: > > Why can't we just move the arch_set_freq_scale() call from cpufreq > > driver to cpufreq core w/o introducing a FIE related driver flag? > > > > Current scenario for Frequency Invariance Engine (FIE) on arm/arm64. > > > > +------------------------------+ +------------------------------+ > > | | | | > > | cpufreq core: | | arch: (arm, arm64) | > > > > | | | | > > | weak arch_set_freq_scale() {}| | | > > | | | | > > +------------------------------+ | | > > | | > > +------------------------------+ | | > > | | | | > > | cpufreq driver: | | | > > | +-----------> arch_set_freq_scale() | > > | | | { | > > +------------------------------+ | if (use counters) | > > | return; | > > +------------------------------+ | ... | > > | | | } | > > | task scheduler: | | | > > | +-----------> arch_scale_freq_tick()* | > > | | | { | > > > > | | | if (!use counters) | > > | | | return; | > > | | | ... | > > | | | } | > > +------------------------------+ +------------------------------+ > > > > * defined as topology_scale_freq_tick() in arm64 > > > > Only Arm/Arm64 defines arch_set_freq_scale() to get the 'legacy' CPUfreq > > based FIE. This would still be the case when we move > > arch_set_freq_scale() from individual cpufreq drivers to cpufreq core. > > > > Arm64 is the only arch which has to runtime-choose between two different > > FIEs. This is currently done by bailing out early in one of the FIE > > functions based on 'use counters'. > > > > X86 (and others) will continue to not define arch_set_freq_scale(). > > > > The issue with CONFIG_BL_SWITCHER (vexpress-spc-cpufreq.c) could be > > solved arm/arm64 internally (arch_topology.c) by putting > > arch_set_freq_scale() under a !CONFIG_BL_SWITCHER guard. > > I doubt that there are any arm bL systems out there running it. At least > > I'm not aware of any complaints due to missing FIE support in bl > > switcher setups so far.
I agree to that.
> Thank you Dietmar, for your review. > > I was trying to suggest the same in my other replies.
I am sorry, I must have overlooked that part in your replies, otherwise I may agreed to it :)
> Rafael, Viresh, would you mind confirming whether you still consider > having an 'opt in' flag is preferable here?
Well, we wanted an opt-in flag instead of an opt-out one. And no flag is certainly better.
-- viresh
|  |