Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [RFC V2 1/6] cpufreq: Replace "max_transition_latency" with "dynamic_switching" | Date | Sat, 15 Jul 2017 00:06:24 +0200 |
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On Friday, July 14, 2017 01:11:58 PM Rafael J. Wysocki wrote: > On Fri, Jul 14, 2017 at 9:01 AM, Dominik Brodowski > <linux@dominikbrodowski.net> wrote: > > On Thu, Jul 13, 2017 at 06:19:53PM +0200, Rafael J. Wysocki wrote: > >> On Thu, Jul 13, 2017 at 7:40 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > >> > There is no limitation in the ondemand or conservative governors which > >> > disallow the transition_latency to be greater than 10 ms. > >> > > >> > The max_transition_latency field is rather used to disallow automatic > >> > dynamic frequency switching for platforms which didn't wanted these > >> > governors to run. > >> > > >> > Replace max_transition_latency with a boolean (dynamic_switching) and > >> > check for transition_latency == CPUFREQ_ETERNAL along with that. This > >> > makes it pretty straight forward to read/understand now. > >> > >> Well, using CPUFREQ_ETERNAL for that on the driver side is still not > >> particularly straightforward IMO, so maybe add a > >> "no_dynamic_switching" to the driver structure and set it to "true" > >> for the one driver in question? > > > > IIRC it's not just one driver which sets the latency to CPUFREQ_ETERNAL, and > > where dynamic switching might be harmful or at least lead to undefined > > behavior. > > OK > > Still, though, using CPUFREQ_ETERNAL to indicate the "no dynamic > switching" condition is somewhat convoluted, so why don't we have a > flag to *explicitly* say that instead? > > Do you know which drivers they are or is it just all drivers that use > CPUFREQ_ETERNAL?
Well, after the $subject patch it effectively is all drivers that use CPUFREQ_ETERNAL anyway, so it looks like we actually can do a complete switch-over.
Thanks, Rafael
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