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

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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: deaba9cff8 ("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>
This commit is contained in:
Uwe Kleine-König 2025-04-05 11:27:13 +02:00 • committed by Uwe Kleine-König
parent 00e53d0f4b
commit fda6e0034e
1 changed files with 3 additions and 9 deletions
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12
drivers/pwm/pwm-stm32.c
View file

@ -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 {