Each devfreq governor can have the different sysfs attributes and features.
In order to provide the only available sysfs attribute to user-space,
add governor attribute flag with DEVFREQ_GOV_ATTR_[attribute name] defintion.
Also, each governor is able to have the specific flag in order to
support specific feature with DEVFREQ_GOV_FLAG_[feature name] defintion
like immutable governor.
According to each governor, can initiate the governor feature and attribute
flags.
[Common sysfs attributes for devfreq class]
And all devfreq governors have to support the following common attributes.
The common attributes are added to devfreq class by default.
- governor
- available_governors
- available_frequencies
- cur_freq
- target_freq
- min_freq
- max_freq
- trans_stat
[Definition for governor attribute flag]
- DEVFREQ_GOV_ATTR_POLLING_INTERVAL to update polling interval for timer.
: /sys/class/devfreq/[devfreq dev name]/polling_interval
- DEVFREQ_GOV_ATTR_TIMER to change the type of timer on either deferrable
or dealyed timer.
: /sys/class/devfreq/[devfreq dev name]/timer
[Definition for governor feature flag]
- DEVFREQ_GOV_FLAG_IMMUTABLE
: If immutable flag is set, governor is never changeable to other governors.
- DEVFREQ_GOV_FLAG_IRQ_DRIVEN
: Devfreq core won't schedule polling work for this governor if value is set.
[Table of governor attribute flags for evfreq governors]
-----------------------------------------------------------------------------
| simple | perfor | power | user | passive | tegra30
| ondemand | mance | save | space| |
------------------------------------------------------------------------------
governor | O | O | O | O | O | O
available_governors | O | O | O | O | O | O
available_frequencies | O | O | O | O | O | O
cur_freq | O | O | O | O | O | O
target_freq | O | O | O | O | O | O
min_freq | O | O | O | O | O | O
max_freq | O | O | O | O | O | O
trans_stat | O | O | O | O | O | O
------------------------------------------------------------------------------
polling_interval | O | X | X | X | X | O
timer | O | X | X | X | X | X
------------------------------------------------------------------------------
immutable | X | X | X | X | O | O
interrupt_driven | X(polling)| X | X | X | X | O (irq)
------------------------------------------------------------------------------
Changes from v2:
- https://lkml.org/lkml/2020/7/13/285 ("[PATCH v2 0/2] PM / devfreq: Add governor flags")
- Hide unsupported sysfs node to user-space instead of checking the permission
of sysfs node.
Chanwoo Choi (2):
PM / devfreq: Add governor feature flag
PM / devfreq: Add governor attribute flag for specifc sysfs nodes
Documentation/ABI/testing/sysfs-class-devfreq | 54 +++---
drivers/devfreq/devfreq.c | 170 +++++++++++-------
drivers/devfreq/governor.h | 30 +++-
drivers/devfreq/governor_passive.c | 2 +-
drivers/devfreq/governor_simpleondemand.c | 2 +
drivers/devfreq/tegra30-devfreq.c | 5 +-
6 files changed, 171 insertions(+), 92 deletions(-)
--
2.17.1
