Commit fda6e003 authored Apr 05, 2025 by Uwe Kleine-König Committed by Uwe Kleine-König Apr 07, 2025

pwm: stm32: Search an appropriate duty_cycle if period cannot be modified

If another channel is already enabled period must not be modified. If
the requested period is smaller than this unchangable period the driver
is still supposed to search a duty_cycle according to the usual rounding
rules.

So don't set the duty_cycle to 0 but continue to determine an
appropriate value for ccr.

Fixes: deaba9cf ("pwm: stm32: Implementation of the waveform callbacks")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/f0c50df31daa3d6069bfa8d7fb3e71fae241b026.1743844730.git.u.kleine-koenig@baylibre.com

Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

parent 00e53d0f

drivers/pwm/pwm-stm32.c

+3 −9

Original line number	Diff line number	Diff line
		@@ -103,22 +103,16 @@ static int stm32_pwm_round_waveform_tohw(struct pwm_chip *chip,
		if (ret)
		goto out;

		/*
		* calculate the best value for ARR for the given PSC, refuse if
		* the resulting period gets bigger than the requested one.
		*/
		arr = mul_u64_u64_div_u64(wf->period_length_ns, rate,
		(u64)NSEC_PER_SEC * (wfhw->psc + 1));
		if (arr <= wfhw->arr) {
		/*
		* requested period is small than the currently
		* requested period is smaller than the currently
		* configured and unchangable period, report back the smallest
		* possible period, i.e. the current state; Initialize
		* ccr to anything valid.
		* possible period, i.e. the current state and return 1
		* to indicate the wrong rounding direction.
		*/
		wfhw->ccr = 0;
		ret = 1;
		goto out;
		}

		} else {