linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Lukasz Luba <lukasz.luba@arm.com>
To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: daniel.lezcano@linaro.org, amitk@kernel.org,
	Dietmar.Eggemann@arm.com, lukasz.luba@arm.com,
	ionela.voinescu@arm.com
Subject: [PATCH v3 1/2] thermal: power allocator: change the 'k_i' coefficient estimation
Date: Fri,  9 Oct 2020 14:58:49 +0100	[thread overview]
Message-ID: <20201009135850.14727-2-lukasz.luba@arm.com> (raw)
In-Reply-To: <20201009135850.14727-1-lukasz.luba@arm.com>

Intelligent Power Allocation (IPA) is built around the PID controller
concept. The initialization code tries to setup the environment based on
the information available in DT or estimate the value based on minimum
power reported by each of the cooling device. The estimation will have an
impact on the PID controller behaviour via the related 'k_po', 'k_pu',
'k_i' coefficients and also on the power budget calculation.

This change prevents the situation when 'k_i' is relatively big compared
to 'k_po' and 'k_pu' values. This might happen when the estimation for
'sustainable_power' returned small value, thus 'k_po' and 'k_pu' are
small.

Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 drivers/thermal/gov_power_allocator.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index e566806f1550..aa35aa6c561c 100644
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -132,6 +132,7 @@ static void estimate_pid_constants(struct thermal_zone_device *tz,
 	int ret;
 	int switch_on_temp;
 	u32 temperature_threshold;
+	s32 k_i;
 
 	ret = tz->ops->get_trip_temp(tz, trip_switch_on, &switch_on_temp);
 	if (ret)
@@ -157,8 +158,11 @@ static void estimate_pid_constants(struct thermal_zone_device *tz,
 		tz->tzp->k_pu = int_to_frac(2 * sustainable_power) /
 			temperature_threshold;
 
-	if (!tz->tzp->k_i || force)
-		tz->tzp->k_i = int_to_frac(10) / 1000;
+	if (!tz->tzp->k_i || force) {
+		k_i = tz->tzp->k_pu / 10;
+		tz->tzp->k_i = k_i > 0 ? k_i : 1;
+	}
+
 	/*
 	 * The default for k_d and integral_cutoff is 0, so we can
 	 * leave them as they are.
-- 
2.17.1


  reply	other threads:[~2020-10-09 13:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09 13:58 [PATCH v3 0/2] Improve the estimations in Intelligent Power Allocation Lukasz Luba
2020-10-09 13:58 ` Lukasz Luba [this message]
2020-10-09 13:58 ` [PATCH v3 2/2] thermal: power allocator: change how estimation code is called Lukasz Luba
2020-10-09 14:23   ` Ionela Voinescu
2020-10-13 16:41   ` Daniel Lezcano
2020-10-29  9:24     ` Lukasz Luba

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201009135850.14727-2-lukasz.luba@arm.com \
    --to=lukasz.luba@arm.com \
    --cc=Dietmar.Eggemann@arm.com \
    --cc=amitk@kernel.org \
    --cc=daniel.lezcano@linaro.org \
    --cc=ionela.voinescu@arm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --subject='Re: [PATCH v3 1/2] thermal: power allocator: change the '\''k_i'\'' coefficient estimation' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).