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The capacitance value is required for the usage of the cpufreq cooling
device and power_allocator thermal governor in the appropriate energy
model.
It helps to compute the power estimated by the SoC at the appropriate
frequency. If it is the frequency of an existing OPP, or at the
frequency of the first OPP above the requested value otherwise.
The power is estimated as P = C * V^2 * f, with C being the SoC's
capacitance and V and f respectively representing the voltage and
frequency of the OPP.
Since AXG SoC doesn't have SCMI protocol support, we need to initialize
capacitance using the 'dynamic-power-coefficient' DT entry. Its value is
retrieved from the vendor kernel, and it gives us the following
freq2power mapping:
+-----------+--------+
| frequency,| power, |
| MHz | uW |
+-----------+--------+
| 100 | 10354 |
+-----------+--------+
| 250 | 27104 |
+-----------+--------+
| 500 | 55447 |
+-----------+--------+
| 667 | 77327 |
+-----------+--------+
| 1000 | 129024 |
+-----------+--------+
| 1200 | 164656 |
+-----------+--------+
| 1296 | 192489 |
+-----------+--------+
| 1416 | 239870 |
+-----------+--------+
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240209212816.11187-3-ddrokosov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
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.