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[thermal:,thermal/next] thermal: power allocator: change the 'k_i' coefficient estimation

Message ID 160734883397.3364.9771166533666047840.tip-bot2@tip-bot2 (mailing list archive)
State Not Applicable, archived
Headers show
Series [thermal:,thermal/next] thermal: power allocator: change the 'k_i' coefficient estimation | expand

Commit Message

thermal-bot for Stanislaw Gruszka Dec. 7, 2020, 1:47 p.m. UTC 
The following commit has been merged into the thermal/next branch of thermal:

Commit-ID:     e34a7233896928e4e39d3cdb201ce605d5b258c2
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux.git//e34a7233896928e4e39d3cdb201ce605d5b258c2
Author:        Lukasz Luba <lukasz.luba@arm.com>
AuthorDate:    Tue, 24 Nov 2020 16:10:23 
Committer:     Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Thu, 26 Nov 2020 17:11:59 +01:00

thermal: power allocator: change the 'k_i' coefficient estimation

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.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201124161025.27694-2-lukasz.luba@arm.com
---
 drivers/thermal/gov_power_allocator.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index b29e21c..2e20085 100644
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -134,6 +134,7 @@  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)
@@ -159,8 +160,11 @@  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.