k_po/k_pu are two proportional term constants and essentially they have
fixed ratio compared with sustainable power. In current implementation,
k_po and k_pu are absolute value after calculation and cannot represent
the ratio relationship with sustainable power; as a result, when change
sustainable power we cannot smoothly change proportional term constant.
So this patch introduces variants k_po_ratio and k_pu_ratio, which
represent the ratio value compared against sustainable power, so smaller
ratio will result in thermal slower ramp. The formulas finally are as
below:
k_pu = k_pu_ratio * sustainable_power /
(desired_temperature - switch_on_temp)
k_po = k_po_ratio * sustainable_power /
(desired_temperature - switch_on_temp)
Signed-off-by: Leo Yan <leo....@linaro.org>
---
drivers/thermal/power_allocator.c | 18 ++++++++++++------
include/linux/thermal.h | 4 ++--
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/thermal/power_allocator.c
b/drivers/thermal/power_allocator.c
index 1246aa6..76d2b47 100644
--- a/drivers/thermal/power_allocator.c
+++ b/drivers/thermal/power_allocator.c
@@ -155,13 +155,11 @@ static void estimate_pid_constants(struct
thermal_zone_device *tz,
if (!temperature_threshold)
return;
- if (!tz->tzp->k_po || force)
- tz->tzp->k_po = int_to_frac(sustainable_power) /
- temperature_threshold;
+ if (!tz->tzp->k_po_ratio || force)
+ tz->tzp->k_po_ratio = 1;
- if (!tz->tzp->k_pu || force)
- tz->tzp->k_pu = int_to_frac(2 * sustainable_power) /
- temperature_threshold;
+ if (!tz->tzp->k_pu_ratio || force)
+ tz->tzp->k_pu_ratio = 2;
if (!tz->tzp->k_i || force)
tz->tzp->k_i = int_to_frac(10) / 1000;
@@ -169,6 +167,11 @@ static void estimate_pid_constants(struct
thermal_zone_device *tz,
* The default for k_d and integral_cutoff is 0, so we can
* leave them as they are.
*/
+
+ tz->tzp->k_po = int_to_frac(tz->tzp->k_po_ratio * sustainable_power) /
+ temperature_threshold;
+ tz->tzp->k_pu = int_to_frac(tz->tzp->k_pu_ratio * sustainable_power) /
+ temperature_threshold;
}
/**
@@ -202,6 +205,9 @@ static u32 pid_controller(struct thermal_zone_device *tz,
if (tz->tzp->sustainable_power) {
sustainable_power = tz->tzp->sustainable_power;
+ estimate_pid_constants(tz, sustainable_power,
+ params->trip_switch_on, control_temp,
+ false);
} else {
sustainable_power = estimate_sustainable_power(tz);
estimate_pid_constants(tz, sustainable_power,
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 613c29b..2638f0b 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -284,13 +284,13 @@ struct thermal_zone_params {
* Proportional parameter of the PID controller when
* overshooting (i.e., when temperature is below the target)
*/
- s32 k_po;
+ s32 k_po, k_po_ratio;
/*
* Proportional parameter of the PID controller when
* undershooting
*/
- s32 k_pu;
+ s32 k_pu, k_pu_ratio;
/* Integral parameter of the PID controller */
s32 k_i;
--
1.9.1
--
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