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fcce7223a5
Problems with existing thermal control loop:
* Not multi-board friendly. thermal.c only supports Link and needs
refactoring. Temp thresholds and fan speeds are hard-coded.
* Only the PECI temp is used to determine the fan speed. Other temp sensors
are ignored.
* Has confusing data structures. Values in the CPU temp thresholds array mix
ACPI thresholds with fan step values.
With this change, the thermal task monitors all temp sensors in order to
perform two completely independent functions:
Function one: Determine if the host needs to be throttled by or informed of
any thermal events.
For thermal events, each temp sensor will have three threshold levels.
TEMP_HOST_WARN
* When any sensor goes above this level, host_throttle_cpu(1) will be called
to ask the CPU to slow itself down.
* When all sensors drop below this level, host_throttle_cpu(0) will be called.
* Exactly AT this level, nothing happens (this provides hysteresis).
TEMP_HOST_HIGH
* When any sensor goes above this level, chipset_throttle_cpu(1) will be
called to slow the CPU down whether it wants to or not.
* When all sensors drop below this level, chipset_throttle_cpu(0) will be
called.
* Exactly AT this level, nothing happens (this provides hysteresis).
TEMP_HOST_SHUTDOWN
* When any sensor is above this level, chipset_force_shutdown() will be
called to halt the CPU.
* Nothing turns the CPU back on again - the user just has to wait for things
to cool off. Pressing the power button too soon will just trigger shutdown
again as soon as the EC can read the host temp.
Function two: Determine the amount of fan cooling needed
For fan cooling, each temp sensor will have two levels.
TEMP_FAN_OFF
* At or below this temperature, no active cooling is needed.
TEMP_FAN_MAX
* At or above this temperature, active cooling should be running at maximum.
The highest level of all temp sensors will be used to request the amount of
active cooling needed. The function pwm_fan_percent_to_rpm() is invoked to
convert the amount of cooling to the target fan RPM.
The default pwm_fan_percent_to_rpm() function converts smoothly between the
configured CONFIG_PWM_FAN_RPM_MIN and CONFIG_PWM_FAN_RPM_MAX for percentages
between 1 and 100. 0% means "off".
The default function probably provide the smoothest and quietest behavior,
but individual boards can provide their own pwm_fan_percent_to_rpm() to
implement whatever curves, hysteresis, feedback, or other hackery they wish.
BUG=chrome-os-partner:20805
BRANCH=none
TEST=manual
Compile-time test with
make BOARD=falco runtests
On the EC console, the existing fan commands should work correctly:
faninfo - display the fan state
fanduty NUM - force the fan PWM to the specified percentage (0-100)
fanset RPM - force the fan to the specified RPM
fanset NUM% - force the fan to the specified percentage (0-100) between
its configured minimum and maximum speeds from board.h
(CONFIG_PWM_FAN_RPM_MIN and CONFIG_PWM_FAN_RPM_MAX)
fanauto - let the EC control the fan automatically
You can test the default pwm_fan_percent_to_rpm() with
fanset 1%
faninfo
The fan should be turning at CONFIG_PWM_FAN_RPM_MIN. Let the EC control it
automatically again with
fanauto
Also on the EC console, the thermal settings can be examined or changed:
> temps
PECI : 327 K = 54 C
ECInternal : 320 K = 47 C
G781Internal : 319 K = 46 C
G781External : 318 K = 45 C
>
> thermalget
sensor warn high shutdown fan_off fan_max name
0 373 387 383 333 363 PECI
1 0 0 0 0 0 ECInternal
2 0 0 0 0 0 G781Internal
3 0 0 0 0 0 G781External
>
> help thermalset
Usage: thermalset sensor warn [high [shutdown [fan_off [fan_max]]]]
set thermal parameters (-1 to skip)
>
> thermalset 2 -1 -1 999
sensor warn high shutdown fan_off fan_max name
0 373 387 383 333 363 PECI
1 0 0 0 0 0 ECInternal
2 0 0 999 0 0 G781Internal
3 0 0 0 0 0 G781External
>
From the host, ectool can be used to get and set these parameters with
nearly identical commands:
ectool thermalget
ectool thermalset 2 -1 -1 999
Change-Id: Idb27977278f766826045fb7d41929953ec6b1cca
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/66688
Reviewed-by: Randall Spangler <rspangler@chromium.org>
35 lines
1.0 KiB
C
35 lines
1.0 KiB
C
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Fan control module for Chrome EC */
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#ifndef __CROS_EC_FAN_H
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#define __CROS_EC_FAN_H
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/**
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* Set the amount of active cooling needed. The thermal control task will call
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* this frequently, and the fan control logic will attempt to provide it.
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*
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* @param pct Percentage of cooling effort needed (0 - 100)
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*/
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void pwm_fan_set_percent_needed(int pct);
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/**
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* This function translates the percentage of cooling needed into a target RPM.
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* The default implementation should be sufficient for most needs, but
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* individual boards may provide a custom version if needed (see config.h).
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*
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* @param pct Percentage of cooling effort needed (always in [0,100])
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* Return Target RPM for fan
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*/
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int pwm_fan_percent_to_rpm(int pct);
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/**
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* Configure the fan GPIOs for the pwm module -- board-specific.
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*/
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void configure_fan_gpios(void);
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#endif /* __CROS_EC_FAN_H */
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