linux.git/Documentation/ABI/testing/sysfs-class-devfreq, branch v5.9

PM / devfreq: Add support delayed timer for polling mode

2020-07-30T08:22:57+00:00

Until now, the devfreq driver using polling mode like simple_ondemand
governor have used only deferrable timer for reducing the redundant
power consumption. It reduces the CPU wake-up from idle due to polling mode
which check the status of Non-CPU device.

But, it has a problem for Non-CPU device like DMC device with DMA operation.
Some Non-CPU device need to do monitor continuously regardless of CPU state
in order to decide the proper next status of Non-CPU device.

So, add support the delayed timer for polling mode to support
the repetitive monitoring. The devfreq driver and user can select
the kind of timer on either deferrable and delayed timer.

For example, change the timer type of DMC device
based on Exynos5422-based Odroid-XU3 as following:

- If want to use deferrable timer as following:
echo deferrable > /sys/class/devfreq/10c20000.memory-controller/timer

- If want to use delayed timer as following:
echo delayed > /sys/class/devfreq/10c20000.memory-controller/timer

Reviewed-by: Bartlomiej Zolnierkiewicz 
Reviewed-by: Lukasz Luba 
Signed-off-by: Chanwoo Choi

PM / devfreq: Add clearing transitions stats

2019-12-30T00:59:05+00:00

Add clearing transition table and time in states devfreq statistics
by writing 0 (zero) to trans_stat file in devfreq sysfs. An example use
is like following:

echo 0 > /sys/class/devfreq/devfreqX/trans_stat

Signed-off-by: Kamil Konieczny 
[cw00.choi: Edit return value if entering the wrong value for reset
 and use arrary3_size() to get the size of 3-dimensional array]
Signed-off-by: Chanwoo Choi

PM / devfreq: Add new name attribute for sysfs

2019-12-30T00:59:05+00:00

The commit 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for
sysfs") changed the node name to devfreq(x). After this commit, it is not
possible to get the device name through /sys/class/devfreq/devfreq(X)/*.

Add new name attribute in order to get device name.

Cc: stable@vger.kernel.org
Fixes: 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs")
Signed-off-by: Chanwoo Choi

ABI: fix some syntax issues at the ABI database

2019-06-14T16:17:11+00:00

On those three files, the ABI representation described at
README are violated.

- at sysfs-bus-iio-proximity-as3935:
	a ':' character is missing after "What"

- at sysfs-class-devfreq:
	there's a typo at Description

- at sysfs-class-cxl, it is using the ":" character at a
	file preamble, causing it to be misinterpreted as a
	tag.

- On the other files, instead of "What", they use "Where".

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Mauro Carvalho Chehab 
Acked-by: Rafael J. Wysocki 
Acked-by: Andrew Donnellan   # cxl
Signed-off-by: Greg Kroah-Hartman

PM / devfreq: add comments and Documentation

2013-06-03T11:20:29+00:00

- Added missing ABI documents
- Added comments to clarify the objectives of functions

Signed-off-by: MyungJoo Ham 
Acked-by: Nishanth Menon 
Acked-by: Rajagopal Venkat

PM / devfreq: Add sysfs node to expose available governors

2012-11-20T09:46:24+00:00

Now that governor list can be variable, knowing the available governors
is useful to be able to select a governor using relevant sysfs node.

Cc: Rajagopal Venkat 
Cc: MyungJoo Ham 
Cc: Kyungmin Park 
Cc: "Rafael J. Wysocki" 
Cc: Kevin Hilman 
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Nishanth Menon 
Signed-off-by: MyungJoo Ham

PM / devfreq: allow sysfs governor node to switch governor

2012-11-20T09:46:23+00:00

This allows us to select governor runtime from the
default configuration without having to rebuild kernel
or the devfreq driver using the sysfs node:
/sys/class/devfreq/.../governor
cat of the governor will return valid governor
and an echo 'governor_name'>governor will switch
governor

Cc: Rajagopal Venkat 
Cc: MyungJoo Ham 
Cc: Kyungmin Park 
Cc: "Rafael J. Wysocki" 
Cc: Kevin Hilman 
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Nishanth Menon 
Acked-by: MyungJoo Ham 
Signed-off-by: MyungJoo Ham

PM / devfreq: Add sysfs node for representing frequency transition information.

2012-11-20T07:05:44+00:00

This patch adds sysfs node which can be used to get information of frequency
transition. It represents transition table which contains total number of transition of
each freqeuncy state and time spent. It is inspired CPUFREQ's status driver.

Signed-off-by: Jonghwa Lee 
[Added Documentation/ABI entry, updated kernel-doc, and resolved merge conflict]
Signed-off-by: MyungJoo Ham

PM / devfreq: Add sysfs node to expose available frequencies

2012-11-20T06:59:32+00:00

devfreq governors such as ondemand are controlled by a min and
max frequency, while governors like userspace governor allow us
to set a specific frequency.
However, for the same specific device, depending on the SoC, the
available frequencies can vary.

So expose the available frequencies as a snapshot over sysfs to
allow informed decisions.

This was inspired by cpufreq framework's equivalent for similar
usage sysfs node: scaling_available_frequencies.

Cc: Rajagopal Venkat 
Cc: MyungJoo Ham 
Cc: Kyungmin Park 
Cc: "Rafael J. Wysocki" 
Cc: Kevin Hilman 
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Nishanth Menon 
Signed-off-by: MyungJoo Ham

PM / devfreq: Add current freq callback in device profile

2012-11-14T23:35:04+00:00

Devfreq returns governor predicted frequency as current frequency
via sysfs interface. But device may not support all frequencies
that governor predicts. So add a callback in device profile to get
current freq from driver. Also add a new sysfs node to expose
governor predicted next target frequency.

Signed-off-by: Rajagopal Venkat 
Acked-by: MyungJoo Ham 
Signed-off-by: Rafael J. Wysocki