The CPU cooling driver (cpu_cooling.c) allows the platform's cpufreq driver to register as a cooling device and cool down the platform by throttling the CPU frequency. In order to be able to auto-register a cpufreq driver as a cooling device from the cpufreq core, we need access to code inside cpu_cooling.c which, in turn, accesses code inside thermal core. CPU_FREQ is a bool while THERMAL is tristate. In some configurations (e.g. allmodconfig), CONFIG_THERMAL ends up as a module while CONFIG_CPU_FREQ is compiled in. This leads to following error: drivers/cpufreq/cpufreq.o: In function `cpufreq_offline': cpufreq.c:(.text+0x407c): undefined reference to `cpufreq_cooling_unregister' drivers/cpufreq/cpufreq.o: In function `cpufreq_online': cpufreq.c:(.text+0x70c0): undefined reference to `of_cpufreq_cooling_register' Given that platforms using CPU_THERMAL usually want it compiled-in so it is available early in boot, make CPU_THERMAL depend on THERMAL being compiled-in instead of allowing it to be a module. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx> --- drivers/thermal/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig index 30323426902e..58bb7d72dc2b 100644 --- a/drivers/thermal/Kconfig +++ b/drivers/thermal/Kconfig @@ -152,6 +152,7 @@ config CPU_THERMAL bool "generic cpu cooling support" depends on CPU_FREQ depends on THERMAL_OF + depends on THERMAL=y help This implements the generic cpu cooling mechanism through frequency reduction. An ACPI version of this already exists -- 2.17.1
