Re: [PATCH] thermal: core: ignore invalid trip temperature

[Lukasz Majewski <l.majewski@samsung.com>]

Hi Zhang,

> 
> For some reason, I did not see the discussion between Lukasz and you
> via email. I can only see it via patchwork.

It is strange. However I'd appreciate to be in CC of this e-mail :-)

> 
> Lukasz,
> 
> if the regulator for thermal unit is not enabled, what will you get?
> temperature 0xFF + trip point -1? or Just temperature 0xFF?

Just 0xFF temperature.

Since 0xFF is larger than SW_TRIP point (mapped to
THERMAL_TRIP_CRITICAL), the code at handle_critical_trips() is executed.

>From my standpoint 0xFF is a possible and valid temperature in Exynos.

Srinivas, what is your error/use case that you need this check?

> I don't think this patch makes any difference in the second case.
> 
> BTW, if you expect some indicator when the thermal unit is not
> enabled, 

Actually, the TMU is enabled and configured, 
Lack of proper regulator (vtmu) for TMU is the culprit of this
situation.

> system critical shutdown is not a proper one, we can either
> check the sysfs I/F, and we can add a warning message here, telling
> that invalid trip point is found.

I think that, it would be a good idea to abort Exynos TMU probe when
"vtmu" regulator is not found.

> 
> thanks,
> rui
> 
> On Wed, 2014-11-12 at 15:43 -0800, Srinivas Pandruvada wrote:
> > Ignore invalid trip temperature less or equal to zero. Some
> > buggy systems have invalid trips, causing system shutdown.
> > 
> > Signed-off-by: Srinivas Pandruvada
> > <srinivas.pandruvada@linux.intel.com> Acked-by: Zhang Rui
> > <rui.zhang@intel.com> ---
> >  drivers/thermal/thermal_core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/thermal/thermal_core.c
> > b/drivers/thermal/thermal_core.c index 9bf10aa..fbf301a 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -368,7 +368,7 @@ static void handle_critical_trips(struct
> > thermal_zone_device *tz, tz->ops->get_trip_temp(tz, trip,
> > &trip_temp); 
> >  	/* If we have not crossed the trip_temp, we do not care. */
> > -	if (tz->temperature < trip_temp)
> > +	if (trip_temp <= 0 || tz->temperature < trip_temp)
> >  		return;
> >  
> >  	trace_thermal_zone_trip(tz, trip, trip_type);
> 
> 
> 
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-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group