pwm: renesas-tpu: Improve maths to compute register settings

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The newly computed register values are intended to exactly match the
previously computed values. The main improvement is that the prescaler
is computed without a loop that involves two divisions in each step.
This uses the fact, that prescalers[i] = 1 << (2 * i).

Assuming a moderately smart compiler, the needed number of divisions for
the case where the requested period is too big, is reduced from 5 to 2.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

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Uwe Kleine-König 2022-04-20 14:12:39 +02:00 • committed by Thierry Reding

parent 208ab8676b

commit 3c173376ef

1 changed files with 35 additions and 15 deletions

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drivers/pwm/pwm-renesas-tpu.c

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