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

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Date:	Thu, 4 Jul 2013 17:19:04 +0000
From:	"R, Durgadoss" <durgadoss.r@...el.com>
To:	Lukasz Majewski <l.majewski@...sung.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Zhang, Rui" <rui.zhang@...el.com>,
	Eduardo Valentin <eduardo.valentin@...com>
CC:	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	"l.majewski@...ess.pl" <l.majewski@...ess.pl>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andre Przywara <andre.przywara@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>
Subject: RE: [PATCH v5 5/7] thermal:boost: Automatic enable/disable of BOOST
 feature

Hi Lukasz,

> -----Original Message-----
> From: linux-pm-owner@...r.kernel.org [mailto:linux-pm-
> owner@...r.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@...r.kernel.org; Linux PM list; Jonghwa Lee; Lukasz Majewski;
> l.majewski@...ess.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@...sung.com>
> Signed-off-by: Myungjoo Ham <myungjoo.ham@...sung.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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