bea2d9868e
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.