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255ab27a07
Delta AFC0612DB-F00 fan has to be set to at least 30% PWM duty cycle to spin up from a stopped state, and can be afterward throttled down to lower PWM duty cycle. Introduce support for operating such fans which need to start at higher PWM duty cycle first and can slow down next. Introduce two new DT properties, "fan-stop-to-start-percent" and "fan-stop-to-start-us". The former describes the minimum percent of fan RPM at which it will surely spin up from stopped state. This value can be found in the fan datasheet and can be converted to PWM duty cycle easily. The "fan-stop-to-start-us" describes the minimum time in microseconds for which the fan has to be set to stopped state start RPM for the fan to surely spin up. Adjust the PWM setting code such that if the PWM duty cycle is below the minimum duty cycle needed by the fan to spin up from stopped state, then first set the PWM duty cycle to the minimum duty cycle needed by the fan to spin up from stopped state, then wait the time necessary for the fan to spin up from stopped state, and finally set the PWM duty cycle to the one desired by user. Signed-off-by: Marek Vasut <marex@denx.de> Message-ID: <20241106185925.223736-2-marex@denx.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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 reStructuredText 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.