brcm2708: organize kernel patches

[openwrt/openwrt.git] / target / linux / brcm2708 / patches-4.19 / 950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch

diff --git a/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch b/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch
new file mode 100644 (file)
index 0000000..af447c1
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch
@@ -0,0 +1,96 @@
+From 05a13bbd7fbb76b4f690042173749a55d85de831 Mon Sep 17 00:00:00 2001
+From: Ram Chandrasekar <rkumbako@codeaurora.org>
+Date: Mon, 7 May 2018 11:54:08 -0600
+Subject: [PATCH] drivers: thermal: step_wise: add support for
+ hysteresis
+
+From: Ram Chandrasekar <rkumbako@codeaurora.org>
+
+Step wise governor increases the mitigation level when the temperature
+goes above a threshold and will decrease the mitigation when the
+temperature falls below the threshold. If it were a case, where the
+temperature hovers around a threshold, the mitigation will be applied
+and removed at every iteration. This reaction to the temperature is
+inefficient for performance.
+
+The use of hysteresis temperature could avoid this ping-pong of
+mitigation by relaxing the mitigation to happen only when the
+temperature goes below this lower hysteresis value.
+
+Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>
+Signed-off-by: Lina Iyer <ilina@codeaurora.org>
+---
+ drivers/thermal/step_wise.c | 33 +++++++++++++++++++++++----------
+ 1 file changed, 23 insertions(+), 10 deletions(-)
+
+--- a/drivers/thermal/step_wise.c
++++ b/drivers/thermal/step_wise.c
+@@ -36,7 +36,7 @@
+  *       for this trip point
+  *    d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
+  *       for this trip point
+- * If the temperature is lower than a trip point,
++ * If the temperature is lower than a hysteresis temperature,
+  *    a. if the trend is THERMAL_TREND_RAISING, do nothing
+  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
+  *       state for this trip point, if the cooling state already
+@@ -127,7 +127,7 @@ static void update_passive_instance(stru
+ 
+ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
+ {
+-      int trip_temp;
++      int trip_temp, hyst_temp;
+       enum thermal_trip_type trip_type;
+       enum thermal_trend trend;
+       struct thermal_instance *instance;
+@@ -135,22 +135,23 @@ static void thermal_zone_trip_update(str
+       int old_target;
+ 
+       if (trip == THERMAL_TRIPS_NONE) {
+-              trip_temp = tz->forced_passive;
++              hyst_temp = trip_temp = tz->forced_passive;
+               trip_type = THERMAL_TRIPS_NONE;
+       } else {
+               tz->ops->get_trip_temp(tz, trip, &trip_temp);
++              hyst_temp = trip_temp;
++              if (tz->ops->get_trip_hyst) {
++                      tz->ops->get_trip_hyst(tz, trip, &hyst_temp);
++                      hyst_temp = trip_temp - hyst_temp;
++              }
+               tz->ops->get_trip_type(tz, trip, &trip_type);
+       }
+ 
+       trend = get_tz_trend(tz, trip);
+ 
+-      if (tz->temperature >= trip_temp) {
+-              throttle = true;
+-              trace_thermal_zone_trip(tz, trip, trip_type);
+-      }
+-
+-      dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
+-                              trip, trip_type, trip_temp, trend, throttle);
++      dev_dbg(&tz->device,
++              "Trip%d[type=%d,temp=%d,hyst=%d]:trend=%d,throttle=%d\n",
++              trip, trip_type, trip_temp, hyst_temp, trend, throttle);
+ 
+       mutex_lock(&tz->lock);
+ 
+@@ -159,6 +160,18 @@ static void thermal_zone_trip_update(str
+                       continue;
+ 
+               old_target = instance->target;
++              throttle = false;
++              /*
++               * Lower the mitigation only if the temperature
++               * goes below the hysteresis temperature.
++               */
++              if (tz->temperature >= trip_temp ||
++                 (tz->temperature >= hyst_temp &&
++                 old_target != THERMAL_NO_TARGET)) {
++                      throttle = true;
++                      trace_thermal_zone_trip(tz, trip, trip_type);
++              }
++
+               instance->target = get_target_state(instance, trend, throttle);
+               dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
+                                       old_target, (int)instance->target);