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Message-ID: <CAJZ5v0iZ=r_jj8unogt28JcmaUYuWFSYZAGXNDyJg3tEQ3x0XA@mail.gmail.com>
Date: Fri, 1 Oct 2021 18:57:59 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: Linux Doc Mailing List <linux-doc@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jonathan Corbet <corbet@....net>,
Amit Kucheria <amitk@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Zhang Rui <rui.zhang@...el.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 1/7] ABI: sysfs-class-thermal: create a file with
thermal_zone ABI
On Thu, Sep 30, 2021 at 11:45 AM Mauro Carvalho Chehab
<mchehab+huawei@...nel.org> wrote:
>
> The thermal ABI is described, together with the internal
> development details at:
>
> Documentation/driver-api/thermal/sysfs-api.rst
>
> Move the sysfs API description to Documentation/ABI,
> ensuring that scripts/get_abi.pl will properly parse it.
So the subject of the patch should be something like
thermal: Move ABI documentation do Documentation/ABI
Also please mention the MAINTAINERS update in the changelog.
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
>
> See [PATCH v2 0/7] at: https://lore.kernel.org/all/cover.1632994837.git.mchehab+huawei@kernel.org/
>
> Documentation/ABI/testing/sysfs-class-thermal | 259 ++++++++++++++++++
> .../driver-api/thermal/sysfs-api.rst | 225 +--------------
> MAINTAINERS | 2 +
> 3 files changed, 264 insertions(+), 222 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-class-thermal
>
> diff --git a/Documentation/ABI/testing/sysfs-class-thermal b/Documentation/ABI/testing/sysfs-class-thermal
> new file mode 100644
> index 000000000000..2c52bb1f864c
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-thermal
> @@ -0,0 +1,259 @@
> +What: /sys/class/thermal/thermal_zoneX/type
> +Description:
> + Strings which represent the thermal zone type.
> + This is given by thermal zone driver as part of registration.
> + E.g: "acpitz" indicates it's an ACPI thermal device.
> + In order to keep it consistent with hwmon sys attribute; this
> + shouldbe a short, lowercase string, not containing spaces nor
> + dashes.
> +
> + RO, Required
> +
> +What: /sys/class/thermal/thermal_zoneX/temp
> +Description:
> + Current temperature as reported by thermal zone (sensor).
> +
> + Unit: millidegree Celsius
> +
> + RO, Required
> +
> +What: /sys/class/thermal/thermal_zoneX/mode
> +Description:
> + One of the predefined values in [enabled, disabled].
> + This file gives information about the algorithm that is
> + currently managing the thermal zone. It can be either default
> + kernel based algorithm or user space application.
> +
> + enabled
> + enable Kernel Thermal management.
> + disabled
> + Preventing kernel thermal zone driver actions upon
> + trip points so that user application can take full
> + charge of the thermal management.
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/policy
> +Description:
> + One of the various thermal governors used for a particular zone.
> +
> + RW, Required
> +
> +What: /sys/class/thermal/thermal_zoneX/available_policies
> +Description:
> + Available thermal governors which can be used for a
> + particular zone.
> +
> + RO, Required
> +
> +What: /sys/class/thermal/thermal_zoneX/trip_point_Y_temp
> +Description:
> + The temperature above which trip point will be fired.
> +
> + Unit: millidegree Celsius
> +
> + RO, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/trip_point_Y_type
> +Description:
> + Strings which indicate the type of the trip point.
> +
> + E.g. it can be one of critical, hot, passive, `active[0-*]`
> + for ACPI thermal zone.
> +
> + RO, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/trip_point_Y_hyst
> +Description:
> + The hysteresis value for a trip point, represented as an
> + integer.
> +
> + Unit: Celsius
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/cdevY
> +Description:
> + Sysfs link to the thermal cooling device node where the sys I/F
> + for cooling device throttling control represents.
> +
> + RO, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/cdevY_trip_point
> +Description:
> + The trip point in this thermal zone which `cdev[0-*]` is
> + associated with; -1 means the cooling device is not
> + associated with any trip point.
> +
> + RO, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/cdevY_weight
> +Description:
> + The influence of `cdev[0-*]` in this thermal zone. This value
> + is relative to the rest of cooling devices in the thermal
> + zone. For example, if a cooling device has a weight double
> + than that of other, it's twice as effective in cooling the
> + thermal zone.
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/emul_temp
> +Description:
> + Interface to set the emulated temperature method in thermal zone
> + (sensor). After setting this temperature, the thermal zone may
> + pass this temperature to platform emulation function if
> + registered or cache it locally. This is useful in debugging
> + different temperature threshold and its associated cooling
> + action. This is write only node and writing 0 on this node
> + should disable emulation.
> +
> + Unit: millidegree Celsius
> +
> + WO, Optional
> +
> + WARNING:
> + Be careful while enabling this option on production systems,
> + because userland can easily disable the thermal policy by simply
> + flooding this sysfs node with low temperature values.
> +
> +
> +What: /sys/class/thermal/thermal_zoneX/k_d
> +Description:
> + The derivative term of the power allocator governor's PID
> + controller. For more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/k_i
> +Description:
> + The integral term of the power allocator governor's PID
> + controller. This term allows the PID controller to compensate
> + for long term drift. For more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/k_po
> +Description:
> + The proportional term of the power allocator governor's PID
> + controller during temperature overshoot. Temperature overshoot
> + is when the current temperature is above the "desired
> + temperature" trip point. For more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/k_pu
> +Description:
> + The proportional term of the power allocator governor's PID
> + controller during temperature undershoot. Temperature undershoot
> + is when the current temperature is below the "desired
> + temperature" trip point. For more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/integral_cutoff
> +Description:
> + Temperature offset from the desired temperature trip point
> + above which the integral term of the power allocator
> + governor's PID controller starts accumulating errors. For
> + example, if integral_cutoff is 0, then the integral term only
> + accumulates error when temperature is above the desired
> + temperature trip point. For more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + Unit: millidegree Celsius
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/slope
> +Description:
> + The slope constant used in a linear extrapolation model
> + to determine a hotspot temperature based off the sensor's
> + raw readings. It is up to the device driver to determine
> + the usage of these values.
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/offset
> +Description:
> + The offset constant used in a linear extrapolation model
> + to determine a hotspot temperature based off the sensor's
> + raw readings. It is up to the device driver to determine
> + the usage of these values.
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/thermal_zoneX/sustainable_power
> +Description:
> + An estimate of the sustained power that can be dissipated by
> + the thermal zone. Used by the power allocator governor. For
> + more information see
> + Documentation/driver-api/thermal/power_allocator.rst
> +
> + Unit: milliwatts
> +
> + RW, Optional
> +
> +What: /sys/class/thermal/cooling_deviceX/type
> +Description:
> + String which represents the type of device, e.g:
> +
> + - for generic ACPI: should be "Fan", "Processor" or "LCD"
> + - for memory controller device on intel_menlow platform:
> + should be "Memory controller".
> +
> + RO, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/max_state
> +Description:
> + The maximum permissible cooling state of this cooling device.
> +
> + RO, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/cur_state
> +Description:
> + The current cooling state of this cooling device.
> + The value can any integer numbers between 0 and max_state:
> +
> + - cur_state == 0 means no cooling
> + - cur_state == max_state means the maximum cooling.
> +
> + RW, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/stats/reset
> +Description:
> + Writing any value resets the cooling device's statistics.
> +
> + WO, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/stats/time_in_state_ms:
> +Description:
> + The amount of time spent by the cooling device in various
> + cooling states. The output will have "<state> <time>" pair
> + in each line, which will mean this cooling device spent <time>
> + msec of time at <state>.
> +
> + Output will have one line for each of the supported states.
> +
> + RO, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/stats/total_trans
> +Description:
> + A single positive value showing the total number of times
> + the state of a cooling device is changed.
> +
> + RO, Required
> +
> +What: /sys/class/thermal/cooling_deviceX/stats/trans_table
> +Description:
> + This gives fine grained information about all the cooling state
> + transitions. The cat output here is a two dimensional matrix,
> + where an entry <i,j> (row i, column j) represents the number
> + of transitions from State_i to State_j. If the transition
> + table is bigger than PAGE_SIZE, reading this will return
> + an -EFBIG error.
> +
> + RO, Required
> diff --git a/Documentation/driver-api/thermal/sysfs-api.rst b/Documentation/driver-api/thermal/sysfs-api.rst
> index c93fa5e961a0..2e0f79a9e2ee 100644
> --- a/Documentation/driver-api/thermal/sysfs-api.rst
> +++ b/Documentation/driver-api/thermal/sysfs-api.rst
> @@ -428,6 +428,9 @@ of thermal zone device. E.g. the generic thermal driver registers one hwmon
> class device and build the associated hwmon sysfs I/F for all the registered
> ACPI thermal zones.
>
> +Please read Documentation/ABI/testing/sysfs-class-thermal for thermal
> +zone and cooling device attribute details.
> +
> ::
>
> /sys/class/hwmon/hwmon[0-*]:
> @@ -437,228 +440,6 @@ ACPI thermal zones.
>
> Please read Documentation/hwmon/sysfs-interface.rst for additional information.
>
> -Thermal zone attributes
> ------------------------
> -
> -type
> - Strings which represent the thermal zone type.
> - This is given by thermal zone driver as part of registration.
> - E.g: "acpitz" indicates it's an ACPI thermal device.
> - In order to keep it consistent with hwmon sys attribute; this should
> - be a short, lowercase string, not containing spaces nor dashes.
> - RO, Required
> -
> -temp
> - Current temperature as reported by thermal zone (sensor).
> - Unit: millidegree Celsius
> - RO, Required
> -
> -mode
> - One of the predefined values in [enabled, disabled].
> - This file gives information about the algorithm that is currently
> - managing the thermal zone. It can be either default kernel based
> - algorithm or user space application.
> -
> - enabled
> - enable Kernel Thermal management.
> - disabled
> - Preventing kernel thermal zone driver actions upon
> - trip points so that user application can take full
> - charge of the thermal management.
> -
> - RW, Optional
> -
> -policy
> - One of the various thermal governors used for a particular zone.
> -
> - RW, Required
> -
> -available_policies
> - Available thermal governors which can be used for a particular zone.
> -
> - RO, Required
> -
> -`trip_point_[0-*]_temp`
> - The temperature above which trip point will be fired.
> -
> - Unit: millidegree Celsius
> -
> - RO, Optional
> -
> -`trip_point_[0-*]_type`
> - Strings which indicate the type of the trip point.
> -
> - E.g. it can be one of critical, hot, passive, `active[0-*]` for ACPI
> - thermal zone.
> -
> - RO, Optional
> -
> -`trip_point_[0-*]_hyst`
> - The hysteresis value for a trip point, represented as an integer
> - Unit: Celsius
> - RW, Optional
> -
> -`cdev[0-*]`
> - Sysfs link to the thermal cooling device node where the sys I/F
> - for cooling device throttling control represents.
> -
> - RO, Optional
> -
> -`cdev[0-*]_trip_point`
> - The trip point in this thermal zone which `cdev[0-*]` is associated
> - with; -1 means the cooling device is not associated with any trip
> - point.
> -
> - RO, Optional
> -
> -`cdev[0-*]_weight`
> - The influence of `cdev[0-*]` in this thermal zone. This value
> - is relative to the rest of cooling devices in the thermal
> - zone. For example, if a cooling device has a weight double
> - than that of other, it's twice as effective in cooling the
> - thermal zone.
> -
> - RW, Optional
> -
> -emul_temp
> - Interface to set the emulated temperature method in thermal zone
> - (sensor). After setting this temperature, the thermal zone may pass
> - this temperature to platform emulation function if registered or
> - cache it locally. This is useful in debugging different temperature
> - threshold and its associated cooling action. This is write only node
> - and writing 0 on this node should disable emulation.
> - Unit: millidegree Celsius
> -
> - WO, Optional
> -
> - WARNING:
> - Be careful while enabling this option on production systems,
> - because userland can easily disable the thermal policy by simply
> - flooding this sysfs node with low temperature values.
> -
> -sustainable_power
> - An estimate of the sustained power that can be dissipated by
> - the thermal zone. Used by the power allocator governor. For
> - more information see Documentation/driver-api/thermal/power_allocator.rst
> -
> - Unit: milliwatts
> -
> - RW, Optional
> -
> -k_po
> - The proportional term of the power allocator governor's PID
> - controller during temperature overshoot. Temperature overshoot
> - is when the current temperature is above the "desired
> - temperature" trip point. For more information see
> - Documentation/driver-api/thermal/power_allocator.rst
> -
> - RW, Optional
> -
> -k_pu
> - The proportional term of the power allocator governor's PID
> - controller during temperature undershoot. Temperature undershoot
> - is when the current temperature is below the "desired
> - temperature" trip point. For more information see
> - Documentation/driver-api/thermal/power_allocator.rst
> -
> - RW, Optional
> -
> -k_i
> - The integral term of the power allocator governor's PID
> - controller. This term allows the PID controller to compensate
> - for long term drift. For more information see
> - Documentation/driver-api/thermal/power_allocator.rst
> -
> - RW, Optional
> -
> -k_d
> - The derivative term of the power allocator governor's PID
> - controller. For more information see
> - Documentation/driver-api/thermal/power_allocator.rst
> -
> - RW, Optional
> -
> -integral_cutoff
> - Temperature offset from the desired temperature trip point
> - above which the integral term of the power allocator
> - governor's PID controller starts accumulating errors. For
> - example, if integral_cutoff is 0, then the integral term only
> - accumulates error when temperature is above the desired
> - temperature trip point. For more information see
> - Documentation/driver-api/thermal/power_allocator.rst
> -
> - Unit: millidegree Celsius
> -
> - RW, Optional
> -
> -slope
> - The slope constant used in a linear extrapolation model
> - to determine a hotspot temperature based off the sensor's
> - raw readings. It is up to the device driver to determine
> - the usage of these values.
> -
> - RW, Optional
> -
> -offset
> - The offset constant used in a linear extrapolation model
> - to determine a hotspot temperature based off the sensor's
> - raw readings. It is up to the device driver to determine
> - the usage of these values.
> -
> - RW, Optional
> -
> -Cooling device attributes
> --------------------------
> -
> -type
> - String which represents the type of device, e.g:
> -
> - - for generic ACPI: should be "Fan", "Processor" or "LCD"
> - - for memory controller device on intel_menlow platform:
> - should be "Memory controller".
> -
> - RO, Required
> -
> -max_state
> - The maximum permissible cooling state of this cooling device.
> -
> - RO, Required
> -
> -cur_state
> - The current cooling state of this cooling device.
> - The value can any integer numbers between 0 and max_state:
> -
> - - cur_state == 0 means no cooling
> - - cur_state == max_state means the maximum cooling.
> -
> - RW, Required
> -
> -stats/reset
> - Writing any value resets the cooling device's statistics.
> - WO, Required
> -
> -stats/time_in_state_ms:
> - The amount of time spent by the cooling device in various cooling
> - states. The output will have "<state> <time>" pair in each line, which
> - will mean this cooling device spent <time> msec of time at <state>.
> - Output will have one line for each of the supported states.
> - RO, Required
> -
> -
> -stats/total_trans:
> - A single positive value showing the total number of times the state of a
> - cooling device is changed.
> -
> - RO, Required
> -
> -stats/trans_table:
> - This gives fine grained information about all the cooling state
> - transitions. The cat output here is a two dimensional matrix, where an
> - entry <i,j> (row i, column j) represents the number of transitions from
> - State_i to State_j. If the transition table is bigger than PAGE_SIZE,
> - reading this will return an -EFBIG error.
> - RO, Required
> -
> 3. A simple implementation
> ==========================
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b765cbc90d1..179eadaebe76 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18653,7 +18653,9 @@ L: linux-pm@...r.kernel.org
> S: Supported
> Q: https://patchwork.kernel.org/project/linux-pm/list/
> T: git git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux.git
> +F: Documentation/ABI/testing/sysfs-class-thermal
> F: Documentation/devicetree/bindings/thermal/
> +F: Documentation/driver-api/thermal/
> F: drivers/thermal/
> F: include/linux/cpu_cooling.h
> F: include/linux/thermal.h
> --
> 2.31.1
>
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