RE: [PATCH v5 5/7] thermal:boost: Automatic enable/disable of BOOST feature

R, Durgadoss
2013-07-04T17:19:12Z

Hi Lukasz,

> -----Original Message-----
> From: linux-pm-owner@vger.kernel.org [mailto:linux-pm-
> owner@vger.kernel.org] On Behalf Of Lukasz Majewski
> Sent: Thursday, July 04, 2013 2:20 PM
> To: Viresh Kumar; Rafael J. Wysocki; Zhang, Rui; Eduardo Valentin
> Cc: cpufreq@vger.kernel.org; Linux PM list; Jonghwa Lee; Lukasz Majewski;
> l.majewski@majess.pl; linux-kernel; Andre Przywara; Daniel Lezcano; Kukjin Kim;
> Myungjoo Ham
> Subject: [PATCH v5 5/7] thermal:boost: Automatic enable/disable of BOOST
> feature
>
> This patch provides auto disable/enable operation for boost. When any
> defined trip point is passed, the boost is disabled.
> In that moment thermal monitor workqueue is woken up and it monitors
> if the device temperature drops below 75% of the smallest trip point.
> When device cools down, the boost is enabled again.
>
> Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
> Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
>
> ---
> Changes for v5:
> - Move boost disable code from cpu_cooling.c to thermal_core.c
> (to handle_non_critical_trips)
> - Extent struct thermal_zone_device by adding overheated bool flag
> - Implement auto enable of boost after device cools down
> - Introduce boost_polling flag, which indicates if thermal uses it's predefined
> pool delay or has woken up thermal workqueue only to wait until device
> cools down.
>
> Changes for v4:
> - New patch
>
> drivers/thermal/thermal_core.c | 31 +++++++++++++++++++++++++++++++
> include/linux/thermal.h | 2 ++
> 2 files changed, 33 insertions(+)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index d755440..12adbad 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -33,6 +33,7 @@
> #include <linux/idr.h>
> #include <linux/thermal.h>
> #include <linux/reboot.h>
> +#include <linux/cpufreq.h>
> #include <net/netlink.h>
> #include <net/genetlink.h>
>
> @@ -326,6 +327,15 @@ static void monitor_thermal_zone(struct
> thermal_zone_device *tz)
> static void handle_non_critical_trips(struct thermal_zone_device *tz,
> int trip, enum thermal_trip_type trip_type)
> {
> + if (cpufreq_boost_supported()) {
> + tz->overheated = true;
> + cpufreq_boost_trigger_state(0);
> + if (!tz->polling_delay) {
> + tz->boost_polling = true;
> + tz->polling_delay = 1000;
> + }
> + }
> +
> if (tz->governor)
> tz->governor->throttle(tz, trip);
> }
> @@ -453,6 +463,27 @@ static void thermal_zone_device_check(struct
> work_struct *work)
> struct thermal_zone_device *tz = container_of(work, struct
> thermal_zone_device,
> poll_queue.work);
> + long trip_temp;
> +
> + if (cpufreq_boost_supported() && tz->overheated) {

Not all thermal drivers support trip points. So, we first need a
if (tz->ops->get_trip_temp) check here.

> + tz->ops->get_trip_temp(tz, 0, &trip_temp);
> + /*
> + * Enable boost again only when current temperature is less
> + * than 75% of trip_temp[0]
> + */
> + if ((tz->temperature + (trip_temp >> 2)) < trip_temp) {

Another way would be to use the get_trend APIs for this thermal zone.
If the trend is cooling we can re-enable boost otherwise not.

> + tz->overheated = false;
> + if (tz->boost_polling) {
> + tz->boost_polling = false;
> + tz->polling_delay = 0;
> + monitor_thermal_zone(tz);
> + }

Overall, I believe this will work well only if the thermal zone is CPU.

Another suggestion is: We tried hard to remove all throttling logic from
thermal_core.c. May be we should include this kind of logic in
step_wise.c ? Rui/Eduardo: Any thoughts on this ?

Thanks,
Durga
> +
> + cpufreq_boost_trigger_state(1);
> + return;
> + }
> + }
> +
> thermal_zone_device_update(tz);
> }
>
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index a386a1c..f1aa3c2 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -172,6 +172,8 @@ struct thermal_zone_device {
> int emul_temperature;
> int passive;
> unsigned int forced_passive;
> + bool overheated;
> + bool boost_polling;
> const struct thermal_zone_device_ops *ops;
> const struct thermal_zone_params *tzp;
> struct thermal_governor *governor;
> --
> 1.7.10.4
>
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