Messages in this thread | | | From | Peter Feuerer <> | Subject | Re: [PATCH] acerhdf: Fix fan activation with new thermal governor | Date | Mon, 25 Feb 2013 11:36:04 +0100 |
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Hi,
sorry for not answering to earlier mails, but sitting in front of the computer and writing English mails is still very exhausting for me.
Borislav Petkov writes:
> On Mon, Feb 25, 2013 at 11:06:40AM +0800, Zhang Rui wrote: >> when the temperature goes up to 50C, will the fan be turned on or not? > > Right, let's first clarify this: > > so we want the fan to go on when it reaches and/or exceeds the 'fanon' > temperature and to go off after it goes under the 'fanoff' temperature. > It is supposed to remain on in the [fanoff,fanon] interval. > > Now, my observation from yesterday was that, if we don't do the > flattening of the abovementioned interval in acerhdf_set_cur_state() but > we simply turn on the fan if we receive state=1 and turn it off when > state=0, the fan gets turned on only for short bursts when the governor > decides it is time to throttle, i.e. the temperature in the zone is > rising and turns it off when the temperature starts to fall again. And > it would turn on the fan at lower temperatures than fanon. > > But this is annoying. The main reason why this acerhdf thing was added > in the first place was to do a better fan control on those machines > because the fans are noisy. Basically, enable the fan only when really > needed - and leave it off when not because it is really annoying. > > When enabled, however, leave it on longer until a safe, 'fanoff' > temperature is reached. > > Am I making more sense now? Peter?
This sounds good, couldn't have stated it more clear. Just one thing to add here: This is standard idea of a "schmitt trigger", we implemented in acerhdf :) http://en.wikipedia.org/wiki/Schmitt_trigger
-- kind regards, --peter;
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