Hi Amit/Rui, > -----Original Message----- > From: Amit Kachhap [mailto:amit.kachhap@xxxxxxxxxx] > Sent: Friday, November 09, 2012 11:52 AM > To: Zhang, Rui > Cc: linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-samsung- > soc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; R, Durgadoss; > lenb@xxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; jonghwa3.lee@xxxxxxxxxxx > Subject: Re: [PATCH 1/4] thermal: Add new thermal trend type to support > quick cooling > > On 9 November 2012 09:21, Zhang Rui <rui.zhang@xxxxxxxxx> wrote: > > On Thu, 2012-11-08 at 11:56 +0530, Amit Kachhap wrote: > >> On 8 November 2012 11:31, Zhang Rui <rui.zhang@xxxxxxxxx> wrote: > >> > On Thu, 2012-11-08 at 09:56 +0530, Amit Daniel Kachhap wrote: > >> >> This modification adds 2 new thermal trend type > THERMAL_TREND_RAISE_FULL > >> >> and THERMAL_TREND_DROP_FULL. This thermal trend can be used to > quickly > >> >> jump to the upper or lower cooling level instead of incremental > increase > >> >> or decrease. > >> > > >> > IMO, what we need is a new more aggressive cooling governor which > always > >> > uses upper limit when the temperature is raising and lower limit when > >> > the temperature is dropping. > >> Yes I agree that a new aggressive governor is the best approach but > >> then i thought adding a new trend type is a simple solution to achieve > >> this and since most of the governor logic might be same as the > >> step-wise governor. I have no objection in doing it through governor. > >> > > > hmmm, > > I think a more proper way is to set the cooling state to upper limit > > when it overheats and reduce the cooling state step by step when the > > temperature drops. > > No actually I was thinking of having a simple governor with a feature > like it only sets to upper level and lower level. Also since the > temperature sensor is capable of interrupting for both increase in > threshold(say 100C) and fall in threshold (say 90C), so polling or > step increments is not needed at all. > Currently stepwise governor governor does that so we might change the > macro name as, > THERMAL_TREND_RAISE_STEP, > THERMAL_TREND_DROP_STEP, > THERMAL_TREND_RAISE_MAX, > THERMAL_TREND_DROP_MAX, > > and file step_wise.c can be named as state_wise.c or trend_wise.c. Yes, in this particular case, we neither need to poll nor do step wise operations. But, most of the other sensors need at least one of them. So, I think we can try it this way: if (sensor supports interrupt) { 'always' use RAISE_MAX and DROP_MAX; } else { Do Step wise operations } And this could be plugged into step wise. I don't think we need a complete new governor just to get this case working. For this to work, we need a way for the governor to know 'whether the sensor can work on interrupt mode'. May be introducing a new field in tzd structure can help us here. I am fine with any name for the governor :-) Thanks, Durga
