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With an input clk rate bigger than 2000000000, scaler would have been zero which then would have resulted in a division by zero. Also the originally implemented algorithm divided by the result of a division. This nearly always looses precision. Consider a requested period of 1000000 ns. With an input clock frequency of 32786885 Hz the hardware was configured with an actual period of 983869.007 ns (PERIOD = 32258) while the hardware can provide 1000003.508 ns (PERIOD = 32787). And note if the input clock frequency was 32786886 Hz instead, the hardware was configured to 1016656.477 ns (PERIOD = 33333) while the optimal setting results in 1000003.477 ns (PERIOD = 32787). This patch implements proper range checking and only divides once for the calculation of period (and similar for duty_cycle). Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de> Tested-by: Lino Sanfilippo <LinoSanfilippo@gmx.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.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.