> -----Original Message-----
> From: Punit Agrawal [mailto:[email protected]]
> Sent: Thursday, March 26, 2015 8:41 PM
> To: Zhang, Rui
> Cc: [email protected]; [email protected]
> Subject: Re: [PATCH V2 1/3] Thermal: initialize thermal zone device correctly
> Importance: High
>
> Zhang Rui <[email protected]> writes:
>
> > After thermal zone device registered, as we have not read any
> > temperature before, thus tz->temperature should not be 0, which
> > actually means 0C, and thermal trend is not available.
> > In this case, we need specially handling for the first
> > thermal_zone_device_update().
> >
> > Both thermal core framework and step_wise governor is enhanced to handle
> this.
> >
> > CC: <[email protected]> #3.18+
> > Tested-by: Manuel Krause <[email protected]>
> > Tested-by: szegad <[email protected]>
> > Tested-by: prash <[email protected]>
> > Tested-by: amish <[email protected]>
> > Tested-by: Matthias <[email protected]>
> > Signed-off-by: Zhang Rui <[email protected]>
> > ---
> > drivers/thermal/step_wise.c | 15 +++++++++++++--
> > drivers/thermal/thermal_core.c | 19 +++++++++++++++++--
> > drivers/thermal/thermal_core.h | 1 +
> > include/linux/thermal.h | 3 +++
> > 4 files changed, 34 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
> > index 5a0f12d..c2bb37c 100644
> > --- a/drivers/thermal/step_wise.c
> > +++ b/drivers/thermal/step_wise.c
> > @@ -63,6 +63,16 @@ static unsigned long get_target_state(struct
> thermal_instance *instance,
> > next_target = instance->target;
> > dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
> >
> > + if (!instance->initialized) {
> > + if (throttle) {
> > + next_target = (cur_state + 1) >= instance->upper ?
> > + instance->upper :
> > + ((cur_state + 1) < instance->lower ?
> > + instance->lower : (cur_state + 1));
> > + } else
> > + next_target = THERMAL_NO_TARGET;
> > + }
> > +
>
> Instead of checking whether the instance has been initialised, you could add
> THERMAL_TREND_INVALID to the thermal_trend enum. That can then be
> handled in the switch case below instead of needing special case handling like
> above.
>
> What do you think?
>
Well, that's what I did in my initial proposal, but I found it is not enough.
Say, for the problem fixed in patch 3/3, when a cooling device is registered
after
the thermal zone, the thermal trend is not THEMAL_TREND_INVALID, but we need
to get a proper cooling state for the newly registered cooling device.
Thus a per thermal_instance flag is introduced instead.
Thanks,
rui
> > switch (trend) {
> > case THERMAL_TREND_RAISING:
> > if (throttle) {
> > @@ -149,7 +159,8 @@ static void thermal_zone_trip_update(struct
> thermal_zone_device *tz, int trip)
> > dev_dbg(&instance->cdev->device, "old_target=%d,
> target=%d\n",
> > old_target, (int)instance->target);
> >
> > - if (old_target == instance->target)
> > + if (instance->initialized &&
> > + old_target == instance->target)
> > continue;
> >
> > /* Activate a passive thermal instance */ @@ -161,7 +172,7
> @@
> > static void thermal_zone_trip_update(struct thermal_zone_device *tz, int
> > trip)
> > instance->target == THERMAL_NO_TARGET)
> > update_passive_instance(tz, trip_type, -1);
> >
> > -
> > + instance->initialized = true;
> > instance->cdev->updated = false; /* cdev needs update */
> > }
> >
>
> [...]
>
> > diff --git a/drivers/thermal/thermal_core.h
> > b/drivers/thermal/thermal_core.h index 0531c75..6d9ffa5 100644
> > --- a/drivers/thermal/thermal_core.h
> > +++ b/drivers/thermal/thermal_core.h
> > @@ -41,6 +41,7 @@ struct thermal_instance {
> > struct thermal_zone_device *tz;
> > struct thermal_cooling_device *cdev;
> > int trip;
> > + bool initialized;
> > unsigned long upper; /* Highest cooling state for this trip point */
> > unsigned long lower; /* Lowest cooling state for this trip point */
> > unsigned long target; /* expected cooling state */
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h index
> > 5eac316..8650b0b 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -40,6 +40,9 @@
> > /* No upper/lower limit requirement */
> > #define THERMAL_NO_LIMIT ((u32)~0)
> >
> > +/* Invalid/uninitialized temperature */
> > +#define THERMAL_TEMP_INVALID -27400
> > +
>
> Did you mean -274000 (note the missing '0') which is < 0K? A comment would be
> helpful for anybody reading the code. Took me a while to parse it.
>
> > /* Unit conversion macros */
> > #define KELVIN_TO_CELSIUS(t) (long)(((long)t-2732 >= 0) ? \
> > ((long)t-2732+5)/10 : ((long)t-2732-5)/10)
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