Messages in this thread | | | Subject | Re: [PATCH] devfreq: Register devfreq as a cooling device | From | Lukasz Luba <> | Date | Thu, 4 Mar 2021 13:47:37 +0000 |
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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
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