For some reason, I thought Rui had picked this already.
Anyways, here are a couple of comments:
On Fri, Oct 30, 2015 at 04:31:47PM +0800, Chen Yu wrote:
> From: Zhang Rui <[email protected]>
>
> 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. And since the step_wise governor
> is the only one that uses trends, so it's the only thermal
> governor that needs to be updated.
>
> 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]>
> Reviewed-by: Javi Merino <[email protected]>
> Signed-off-by: Zhang Rui <[email protected]>
> Signed-off-by: Chen Yu <[email protected]>
> ---
> drivers/thermal/step_wise.c | 17 +++++++++++++++--
> drivers/thermal/thermal_core.c | 19 +++++++++++++++++--
> drivers/thermal/thermal_core.h | 1 +
I would prefer if you could split this patch in two. One for thermal
core another one for step wise.
> include/linux/thermal.h | 3 +++
> 4 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
> index 2f9f708..ea9366a 100644
> --- a/drivers/thermal/step_wise.c
> +++ b/drivers/thermal/step_wise.c
> @@ -63,6 +63,19 @@ 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;
> + }
> +
> + return next_target;
> + }
> +
> switch (trend) {
> case THERMAL_TREND_RAISING:
> if (throttle) {
> @@ -149,7 +162,7 @@ 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 +174,7 @@ 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 */
> }
>
Considering that I understood the problem and your proposal well, I
would say these changes on step wise are the perfect case for setting up
a step_wise.bind_to_tz(). bind_to_tz() is already designed as an
opportunity for governor to check the thermal zone status at the time of
binding. Remember that moving to bind_to_tz() covers not only
registration time, but governor switching too (say, user chooses
user_space, then step_wise).
The above code seams to be correct, but after reviewing the code
of step_wise.throttle(), I would say it is already complicated and
deserves simplification, when possible.
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index d9e525c..682bc1e 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -532,8 +532,22 @@ static void update_temperature(struct thermal_zone_device *tz)
> mutex_unlock(&tz->lock);
>
> trace_thermal_temperature(tz);
> - dev_dbg(&tz->device, "last_temperature=%d, current_temperature=%d\n",
> - tz->last_temperature, tz->temperature);
> + if (tz->last_temperature == THERMAL_TEMP_INVALID)
> + dev_dbg(&tz->device, "last_temperature N/A, current_temperature=%d\n",
> + tz->temperature);
> + else
> + dev_dbg(&tz->device, "last_temperature=%d, current_temperature=%d\n",
> + tz->last_temperature, tz->temperature);
> +}
> +
> +static void thermal_zone_device_reset(struct thermal_zone_device *tz)
> +{
> + struct thermal_instance *pos;
> +
> + tz->temperature = THERMAL_TEMP_INVALID;
> + tz->passive = 0;
> + list_for_each_entry(pos, &tz->thermal_instances, tz_node)
> + pos->initialized = false;
> }
>
> void thermal_zone_device_update(struct thermal_zone_device *tz)
> @@ -1900,6 +1914,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>
> INIT_DELAYED_WORK(&(tz->poll_queue), thermal_zone_device_check);
>
> + thermal_zone_device_reset(tz);
> thermal_zone_device_update(tz);
>
> return tz;
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index d7ac1fc..749d41a 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 157d366..5bcabc7 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -43,6 +43,9 @@
> /* Default weight of a bound cooling device */
> #define THERMAL_WEIGHT_DEFAULT 0
>
> +/* use value, which < 0K, to indicate an invalid/uninitialized temperature */
> +#define THERMAL_TEMP_INVALID -274000
> +
> /* Unit conversion macros */
> #define KELVIN_TO_CELSIUS(t) (long)(((long)t-2732 >= 0) ? \
> ((long)t-2732+5)/10 : ((long)t-2732-5)/10)
> --
> 1.8.4.2
>