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SubjectRe: [PATCH v1 00/10] cpufreq: Add flag to auto-register as cooling device
On Thu, Jan 17, 2019 at 6:49 AM Viresh Kumar <> wrote:
> On 14-01-19, 22:04, Amit Kucheria wrote:
> > Add a flag to be used by cpufreq drivers to tell cpufreq core to
> > auto-register themselves as a thermal cooling device.
> >
> > There series converts over all the drivers except arm_big_little.c.
> > Tested on SDM845 with the qcom-cpufreq-hw driver. Only compile-tested the
> > others.
> >
> > Things needing fixing:
> > - Look at how to detect that we're not in IKS mode in arm_big_little's
> > .ready callback.
> is_bL_switching_enabled() lets you know if IKS is enabled or not.
> Set/clear flag conditionally before the cpufreq-driver is registered,
> based on the output of is_bL_switching_enabled().
> > - The other pending issue is to fix allmodconfig that leaves us with
> > CPU_FREQ=y and THERMAL=m (CPU_THERMAL=y). That leads to undefined
> > references for functions defined in cpu_cooling.c
> Okay, that's a terrible thing and the solution looks to be rather
> difficult.
> For others who may not be aware of the issue here, currently the
> cpufreq drivers use helpers of cpu_cooling.c (CONFIG_CPU_THERMAL),
> which uses helpers of the thermal core (CONFIG_THERMAL).
> CONFIG_THERMAL is defined as tristate and CONFIG_CPU_THERMAL as bool
> in Kconfigs.

And CONFIG_CPU_THERMAL is defined under "if THERMAL".

> The cpufreq drivers using the cpu_cooling.c file have this in their
> Kconfig entry:
> # if CPU_THERMAL is on and THERMAL=m, ARM_BIT_LITTLE_CPUFREQ cannot be =y
> # depends on !CPU_THERMAL || THERMAL
> This series now places the cpufreq core in place of the cpufreq driver
> and it messes up everything. It is not just about allmodconfig, but
> any configuration which makes the compilation fail.
> What are the solutions we have now ?
> 1. Have following for CONFIG_CPU_FREQ
> depends on !CPU_THERMAL || THERMAL

Sorry, but this makes my teeth hurt.

> The platforms which don't need CPU_THERMAL (like x86) should not
> enable CPU_THERMAL anymore if they want CONFIG_THERMAL=m.
> @amit: If this gets accepted, please update the Kconfig entries for
> all those drivers to not have above lines anymore.
> - Change CONFIG_THERMAL to bool instead of tristate ?
> - Anything else ?

The design in the thermal subsystem seems to be upside-down.
Non-modular code should never be made depend on anything only defined
in a module.

Would an explicit "select THERMAL" under CPU_THERMAL cause THERMAL to be 'y'?

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