linux-stable.git/drivers/thermal/step_wise.c, branch linux-4.1.y

thermal/drivers/step_wise: Fix temperature regulation misbehavior

2018-01-17T17:55:39+00:00

[ Upstream commit 07209fcf33542c1ff1e29df2dbdf8f29cdaacb10 ]

There is a particular situation when the cooling device is cpufreq and the heat
dissipation is not efficient enough where the temperature increases little by
little until reaching the critical threshold and leading to a SoC reset.

The behavior is reproducible on a hikey6220 with bad heat dissipation (eg.
stacked with other boards).

Running a simple C program doing while(1); for each CPU of the SoC makes the
temperature to reach the passive regulation trip point and ends up to the
maximum allowed temperature followed by a reset.

This issue has been also reported by running the libhugetlbfs test suite.

What is observed is a ping pong between two cpu frequencies, 1.2GHz and 900MHz
while the temperature continues to grow.

It appears the step wise governor calls get_target_state() the first time with
the throttle set to true and the trend to 'raising'. The code selects logically
the next state, so the cpu frequency decreases from 1.2GHz to 900MHz, so far so
good. The temperature decreases immediately but still stays greater than the
trip point, then get_target_state() is called again, this time with the
throttle set to true *and* the trend to 'dropping'. From there the algorithm
assumes we have to step down the state and the cpu frequency jumps back to
1.2GHz. But the temperature is still higher than the trip point, so
get_target_state() is called with throttle=1 and trend='raising' again, we jump
to 900MHz, then get_target_state() is called with throttle=1 and
trend='dropping', we jump to 1.2GHz, etc ... but the temperature does not
stabilizes and continues to increase.

[  237.922654] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1
[  237.922678] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1
[  237.922690] thermal cooling_device0: cur_state=0
[  237.922701] thermal cooling_device0: old_target=0, target=1
[  238.026656] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1
[  238.026680] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=1
[  238.026694] thermal cooling_device0: cur_state=1
[  238.026707] thermal cooling_device0: old_target=1, target=0
[  238.134647] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1
[  238.134667] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1
[  238.134679] thermal cooling_device0: cur_state=0
[  238.134690] thermal cooling_device0: old_target=0, target=1

In this situation the temperature continues to increase while the trend is
oscillating between 'dropping' and 'raising'. We need to keep the current state
untouched if the throttle is set, so the temperature can decrease or a higher
state could be selected, thus preventing this oscillation.

Keeping the next_target untouched when 'throttle' is true at 'dropping' time
fixes the issue.

The following traces show the governor does not change the next state if
trend==2 (dropping) and throttle==1.

[ 2306.127987] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1
[ 2306.128009] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1
[ 2306.128021] thermal cooling_device0: cur_state=0
[ 2306.128031] thermal cooling_device0: old_target=0, target=1
[ 2306.231991] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1
[ 2306.232016] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=1
[ 2306.232030] thermal cooling_device0: cur_state=1
[ 2306.232042] thermal cooling_device0: old_target=1, target=1
[ 2306.335982] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1
[ 2306.336006] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=1
[ 2306.336021] thermal cooling_device0: cur_state=1
[ 2306.336034] thermal cooling_device0: old_target=1, target=1
[ 2306.439984] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1
[ 2306.440008] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=0
[ 2306.440022] thermal cooling_device0: cur_state=1
[ 2306.440034] thermal cooling_device0: old_target=1, target=0

[ ... ]

After a while, if the temperature continues to increase, the next state becomes
2 which is 720MHz on the hikey. That results in the temperature stabilizing
around the trip point.

[ 2455.831982] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1
[ 2455.832006] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=0
[ 2455.832019] thermal cooling_device0: cur_state=1
[ 2455.832032] thermal cooling_device0: old_target=1, target=1
[ 2455.935985] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1
[ 2455.936013] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=0
[ 2455.936027] thermal cooling_device0: cur_state=1
[ 2455.936040] thermal cooling_device0: old_target=1, target=1
[ 2456.043984] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=0,throttle=1
[ 2456.044009] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=0,throttle=0
[ 2456.044023] thermal cooling_device0: cur_state=1
[ 2456.044036] thermal cooling_device0: old_target=1, target=1
[ 2456.148001] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=1,throttle=1
[ 2456.148028] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=1,throttle=1
[ 2456.148042] thermal cooling_device0: cur_state=1
[ 2456.148055] thermal cooling_device0: old_target=1, target=2
[ 2456.252009] thermal thermal_zone0: Trip0[type=1,temp=65000]:trend=2,throttle=1
[ 2456.252041] thermal thermal_zone0: Trip1[type=1,temp=75000]:trend=2,throttle=0
[ 2456.252058] thermal cooling_device0: cur_state=2
[ 2456.252075] thermal cooling_device0: old_target=2, target=1

IOW, this change is needed to keep the state for a cooling device if the
temperature trend is oscillating while the temperature increases slightly.

Without this change, the situation above leads to a catastrophic crash by a
hardware reset on hikey. This issue has been reported to happen on an OMAP
dra7xx also.

Signed-off-by: Daniel Lezcano 
Cc: Keerthy 
Cc: John Stultz 
Cc: Leo Yan 
Tested-by: Keerthy 
Reviewed-by: Keerthy 
Signed-off-by: Eduardo Valentin 
Signed-off-by: Sasha Levin

Thermal: initialize thermal zone device correctly

2016-02-01T19:45:56+00:00

[ Upstream commit bb431ba26c5cd0a17c941ca6c3a195a3a6d5d461 ]

After thermal zone device registered, as we have not read any
temperature before, thus tz->temperature should not be 0,
which actually means 0C, and thermal trend is not available.
In this case, we need specially handling for the first
thermal_zone_device_update().

Both thermal core framework and step_wise governor is
enhanced to handle this. And since the step_wise governor
is the only one that uses trends, so it's the only thermal
governor that needs to be updated.

CC:  #3.18+
Tested-by: Manuel Krause 
Tested-by: szegad 
Tested-by: prash 
Tested-by: amish 
Tested-by: Matthias 
Reviewed-by: Javi Merino 
Signed-off-by: Zhang Rui 
Signed-off-by: Chen Yu 
Signed-off-by: Sasha Levin

thermal: step_wise: spelling fixes

2015-02-06T08:35:00+00:00

Signed-off-by: Brian Norris 
Signed-off-by: Zhang Rui

Merge branch 'thermal-core-fix' of .git into next

2014-10-11T01:28:13+00:00

thermal: step_wise: fix: Prevent from binary overflow when trend is dropping

2014-10-09T02:44:01+00:00

It turns out that some boards can have instance->lower greater than 0 and
when thermal trend is dropping it results with next_target equal to -1.

Since the next_target is defined as unsigned long it is interpreted as
0xFFFFFFFF and larger than instance->upper.
As a result the next_target is set to instance->upper which ramps up to
maximal cooling device target when the temperature is steadily decreasing.

Signed-off-by: Lukasz Majewski 
Signed-off-by: Zhang Rui

thermal: trace: Trace when temperature is above a trip point

2014-07-29T13:28:43+00:00

Create a new event to trace when the temperature is above a trip
point. Use the trace-point when handling non-critical and critical
trip pionts.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Cc: Steven Rostedt 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Signed-off-by: Punit Agrawal 
Signed-off-by: Eduardo Valentin

thermal: debug: add debug statement for core and step_wise

2014-01-02T02:52:48+00:00

To ease debugging thermal problem, add these dynamic debug statements
so that user do not need rebuild kernel to see these info.

Based on a patch from Zhang Rui for debugging on bugzilla:
https://bugzilla.kernel.org/attachment.cgi?id=98671

A sample output after we turn on dynamic debug with the following cmd:
# echo 'module thermal_sys +fp' > /sys/kernel/debug/dynamic_debug/control
is like:

[  355.147627] update_temperature: thermal thermal_zone0: last_temperature=52000, current_temperature=55000
[  355.147636] thermal_zone_trip_update: thermal thermal_zone0: Trip1[type=1,temp=79000]:trend=2,throttle=0
[  355.147644] get_target_state: thermal cooling_device8: cur_state=0
[  355.147647] thermal_zone_trip_update: thermal cooling_device8: old_target=-1, target=-1
[  355.147652] get_target_state: thermal cooling_device7: cur_state=0
[  355.147655] thermal_zone_trip_update: thermal cooling_device7: old_target=-1, target=-1
[  355.147660] get_target_state: thermal cooling_device6: cur_state=0
[  355.147663] thermal_zone_trip_update: thermal cooling_device6: old_target=-1, target=-1
[  355.147668] get_target_state: thermal cooling_device5: cur_state=0
[  355.147671] thermal_zone_trip_update: thermal cooling_device5: old_target=-1, target=-1
[  355.147678] thermal_zone_trip_update: thermal thermal_zone0: Trip2[type=0,temp=90000]:trend=1,throttle=0
[  355.147776] get_target_state: thermal cooling_device0: cur_state=0
[  355.147783] thermal_zone_trip_update: thermal cooling_device0: old_target=-1, target=-1
[  355.147792] thermal_zone_trip_update: thermal thermal_zone0: Trip3[type=0,temp=80000]:trend=1,throttle=0
[  355.147845] get_target_state: thermal cooling_device1: cur_state=0
[  355.147849] thermal_zone_trip_update: thermal cooling_device1: old_target=-1, target=-1
[  355.147856] thermal_zone_trip_update: thermal thermal_zone0: Trip4[type=0,temp=70000]:trend=1,throttle=0
[  355.147904] get_target_state: thermal cooling_device2: cur_state=0
[  355.147908] thermal_zone_trip_update: thermal cooling_device2: old_target=-1, target=-1
[  355.147915] thermal_zone_trip_update: thermal thermal_zone0: Trip5[type=0,temp=60000]:trend=1,throttle=0
[  355.147963] get_target_state: thermal cooling_device3: cur_state=0
[  355.147967] thermal_zone_trip_update: thermal cooling_device3: old_target=-1, target=-1
[  355.147973] thermal_zone_trip_update: thermal thermal_zone0: Trip6[type=0,temp=55000]:trend=1,throttle=1
[  355.148022] get_target_state: thermal cooling_device4: cur_state=0
[  355.148025] thermal_zone_trip_update: thermal cooling_device4: old_target=-1, target=1
[  355.148036] thermal_cdev_update: thermal cooling_device4: zone0->target=1
[  355.169279] thermal_cdev_update: thermal cooling_device4: set to state 1

Signed-off-by: Aaron Lu 
Acked-by: Eduardo Valentin 
Signed-off-by: Zhang Rui

thermal: step_wise: return instance->target by default

2013-08-15T07:49:20+00:00

In case the trend is not changing or when there is no
request for throttling, it is expected that the instance
would not change its requested target. This patch improves
the code implementation to cover for this expected behavior.

With current implementation, the instance will always
reset to cdev.cur_state, even in not expected cases,
like those mentioned above.

This patch changes the step_wise governor implementation
of get_target so that we accomplish:
(a) - default value will be current instance->target, so
we do not change the thermal instance target unnecessarily.
(b) - the code now it is clear about what is the intention.
There is a clear statement of what are the expected outcomes
(c) - removal of hardcoded constants, now it is put in use
the THERMAL_NO_TARGET macro.
(d) - variable names are also improved so that reader can
clearly understand the difference between instance cur target,
next target and cdev cur_state.

Cc: Zhang Rui 
Cc: Durgadoss R 
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reported-by: Ruslan Ruslichenko 
Signed-of-by: Eduardo Valentin 
Signed-off-by: Zhang Rui

thermal: step_wise: cdev only needs update on a new target state

2013-08-15T07:48:59+00:00

The cooling device only needs update on a new target state.  Since we
already check old target in thermal_zone_trip_update(), we can do one
more check to see if it's a new target state.  If not, we can reasonably
save some uncecesary code execution.

Signed-off-by: Shawn Guo 
Acked-by: Eduardo Valentin 
Signed-off-by: Zhang Rui

Thermal: build thermal governors into thermal_sys module

2013-04-14T15:28:43+00:00

The thermal governors are part of the thermal framework,
rather than a seperate feature/module.
Because the generic thermal layer can not work without
thermal governors, and it must load the thermal governors
during its initialization.

Build them into one module in this patch.

This also fix a problem that the generic thermal layer does not
work when CONFIG_THERMAL=m and CONFIG_THERMAL_GOV_XXX=y.

Signed-off-by: Zhang Rui 
Acked-by: Eduardo Valentin 
Acked-by: Durgadoss R