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Add additional attributes, which helps in implementing algorithm in
the user space to optimize fan control. These attributes are presented
in the same directory as the existing performance state attributes.
Additional attributes:
1. Support of fine grain control
Publish support of presence of fine grain control so that fan speed
can be tuned correctly. This attribute is called "fine_grain_control".
2. fan speed
Publish the actual fan rpm in sysfs. Knowing fan rpm is helpful to
reduce noise level and use passive control instead. Also fan performance
may not be same over time, so the same control value may not be enough
to run the fan at a speed. So a feedback value of speed is helpful. This
sysfs attribute is called "fan_speed_rpm".
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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When _FIF object specifies support for fine grain control, then fan speed
can be set from 0 to 100% with the recommended minimum "step size" via
_FSL object. Here the control value doesn't need to match any value from
_FPS object.
Currently we have a simple solution implemented which just pick maximum
control value from _FPS to display the actual state, but this is not
optimal when there is a big window between two control values in
_FPS. Also there is no way to set to any speed which doesn't match
control values in _FPS. The system firmware can start the fan at speed
which doesn't match any control value.
To support fine grain control (when supported) via thermal sysfs:
- cooling device max state is not _FPS state count but it will be
100 / _FIF.step_size
Step size can be from 1 to 9.
- cooling device current state is _FST.control / _FIF.step_size
- cooling device set state will set the control value
cdev.curr_state * _FIF.step_size plus any adjustment for 100%.
By the spec, when control value do not sum to 100% because of
_FIF.step_size, OSPM may select an appropriate ending Level increment
to reach 100%.
There is no rounding during calculation. For example if step size
is 6:
thermal sysfs cooling device max_state = 100/6 = 16
So user can set any value from 0-16.
If the system boots with a _FST.control which is not multiples
of step_size, the thermal sysfs cur_state will be based on the
range. For example for step size = 6:
_FST.control thermal sysfs cur_state
------------------------------------------------
0-5 0
6-11 1
..
..
90-95 15
96-100 16
While setting the _FST.control, the compensation will be at
the last step for cur_state = 16, which will set the _FST.control
to 100.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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We don't need u64 to store the information about _FIF. There are two
booleans (fine_grain_ctrl and low_speed_notification) and one field
step_size which can take value from 1-9. There are no internal users
of revision field. So convert all fields to u8, by not directly
extracting the _FIF info the struct. Use an intermediate buffer to
extract and assign.
This will help to do u32 math using these fields. No functional
changes are expected.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Move the functionality of creation of sysfs attributes under acpi device
to a new file fan_attr.c. This cleans up the core fan code, which just
use thermal sysfs interface. The original fan.c is renamed to
fan_core.c.
No functional changes are expected.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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