Hi Daniel, On 3/4/21 12:50 PM, Daniel Lezcano wrote:
Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device. There are no so many and actually it makes more sense to register the devfreq device when adding it. Consequently, every devfreq becomes a cooling device like cpufreq is. Having a devfreq being registered as a cooling device can not mitigate a thermal zone if it is not bound to this one. Thus, the current configurations are not impacted by this change.
There are also different type of devices, which register into devfreq framework like NoC buses, UFS/eMMC, jpeg and video accelerators, ISP, etc. In some platforms there are plenty of those devices and they all would occupy memory due to private freq_table in devfreq_cooling, function: devfreq_cooling_gen_tables(). IIRC in OdroidXU4 there are ~20 devfreq devs for NoC buses. It's true that they will not affect thermal zones, but unnecessarily, they all will show up in the /sys/class/thermal/ as thermal-devfreq-X. IMO the devfreq shouldn't be tight with devfreq cooling thermal. CpuFreq is different because it handles only CPUs. Here we have many different devices. Regards, Lukasz
