From: Lukasz Luba Date: Tue, 24 Nov 2020 16:10:23 +0000 (+0000) Subject: thermal: power allocator: change the 'k_i' coefficient estimation X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e34a7233896928e4e39d3cdb201ce605d5b258c2;p=linux.git 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 Reviewed-by: Ionela Voinescu Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20201124161025.27694-2-lukasz.luba@arm.com --- diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c index b29e21c56a4fb..2e20085ed2171 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.