Re: [PATCH] ACPI thermal: do not always returnTHERMAL_TREND_RAISING for active trip points

From: Pavel Machek
Date: Sat Apr 27 2013 - 06:23:56 EST


> Commit 4ae46befb49d4173122e0afa995c4e93d01948a2
> introduces a regression that the fan is always on
> even if the system is in idle state.
> My original idea in that commit is that:
> when the current temperature is above the trip point,
> keep the fan on, even if the temperature is dropping.
> when the current temperature is below the trip point,
> turn on the fan when the temperature is raising,
> turn off the fan when the temperature is dropping.

Is that even right algoritm?

Assume I'm running at very cold room, lets say -10C. Assume idle CPU
will hover around 30C with no fan, or hover around 10C with fan
running, trip point being 50C.

You _could_ leave fan off until 50C, having silent, passively cooled

What it will do instead is annoyingly pulse fan at 10C.

(cesky, pictures)
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