6.6-stable review patch. If anyone has any objections, please let me know.
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From: Di Shen di.shen@unisoc.com
[ Upstream commit e95fa7404716f6e25021e66067271a4ad8eb1486 ]
Commit 0952177f2a1f ("thermal/core/power_allocator: Update once cooling devices when temp is low") adds an update flag to avoid triggering a thermal event when there is no need, and the thermal cdev is updated once when the temperature is low.
But when the trips are writable, and switch_on_temp is set to be a higher value, the cooling device state may not be reset to 0, because last_temperature is smaller than switch_on_temp.
For example: First: switch_on_temp=70 control_temp=85; Then userspace change the trip_temp: switch_on_temp=45 control_temp=55 cur_temp=54
Then userspace reset the trip_temp: switch_on_temp=70 control_temp=85 cur_temp=57 last_temp=54
At this time, the cooling device state should be reset to 0. However, because cur_temp(57) < switch_on_temp(70) last_temp(54) < switch_on_temp(70) ----> update = false, update is false, the cooling device state can not be reset.
Using the observation that tz->passive can also be regarded as the temperature status, set the update flag to the tz->passive value.
When the temperature drops below switch_on for the first time, the states of cooling devices can be reset once, and tz->passive is updated to 0. In the next round, because tz->passive is 0, cdev->state will not be updated.
By using the tz->passive value as the "update" flag, the issue above can be solved, and the cooling devices can be updated only once when the temperature is low.
Fixes: 0952177f2a1f ("thermal/core/power_allocator: Update once cooling devices when temp is low") Cc: 5.13+ stable@vger.kernel.org # 5.13+ Suggested-by: Wei Wang wvw@google.com Signed-off-by: Di Shen di.shen@unisoc.com Reviewed-by: Lukasz Luba lukasz.luba@arm.com [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/thermal/gov_power_allocator.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c index 1faf55446ba2..fc969642f70b 100644 --- a/drivers/thermal/gov_power_allocator.c +++ b/drivers/thermal/gov_power_allocator.c @@ -715,7 +715,7 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip_id)
ret = __thermal_zone_get_trip(tz, params->trip_switch_on, &trip); if (!ret && (tz->temperature < trip.temperature)) { - update = (tz->last_temperature >= trip.temperature); + update = tz->passive; tz->passive = 0; reset_pid_controller(params); allow_maximum_power(tz, update);