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

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Thu, 2014-11-20 at 11:25 +0100, Lukasz Majewski wrote: 
> 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?
critical trip point < 0 because buggy FW and temp read is more than trip
temp.

Thanks,
Srinivas 
> 
> > 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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> 
> 
>