[PATCH AUTOSEL 6.14 08/34] pwm: Let pwm_set_waveform() succeed even if lowlevel driver rounded up

Sasha Levin
2025-04-14T13:26:29Z

From: Uwe Kleine-König <u.kleine-koenig@baylibre.com>

[ Upstream commit 00e53d0f4baedd72196b65f00698b2a5a537dc2b ]

Waveform parameters are supposed to be rounded down to the next value
possible for the hardware. However when a requested value is too small,
.round_waveform_tohw() is supposed to pick the next bigger value and
return 1. Let pwm_set_waveform() behave in the same way.

This creates consistency between pwm_set_waveform_might_sleep() with
exact=false and pwm_round_waveform_might_sleep() +
pwm_set_waveform_might_sleep() with exact=true.

The PWM_DEBUG rounding check has to be adapted to only trigger if no
uprounding happend.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/353dc6ae31be815e41fd3df89c257127ca0d1a09.1743844730.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pwm/core.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index ccd54c089bab8..0e4df71c2cef1 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -322,7 +322,7 @@ static int __pwm_set_waveform(struct pwm_device *pwm,
const struct pwm_ops *ops = chip->ops;
char wfhw[WFHWSIZE];
struct pwm_waveform wf_rounded;
- int err;
+ int err, ret_tohw;

BUG_ON(WFHWSIZE < ops->sizeof_wfhw);

@@ -332,16 +332,16 @@ static int __pwm_set_waveform(struct pwm_device *pwm,
if (!pwm_wf_valid(wf))
return -EINVAL;

- err = __pwm_round_waveform_tohw(chip, pwm, wf, &wfhw);
- if (err)
- return err;
+ ret_tohw = __pwm_round_waveform_tohw(chip, pwm, wf, &wfhw);
+ if (ret_tohw < 0)
+ return ret_tohw;

if ((IS_ENABLED(CONFIG_PWM_DEBUG) || exact) && wf->period_length_ns) {
err = __pwm_round_waveform_fromhw(chip, pwm, &wfhw, &wf_rounded);
if (err)
return err;

- if (IS_ENABLED(CONFIG_PWM_DEBUG) && !pwm_check_rounding(wf, &wf_rounded))
+ if (IS_ENABLED(CONFIG_PWM_DEBUG) && ret_tohw == 0 && !pwm_check_rounding(wf, &wf_rounded))
dev_err(&chip->dev, "Wrong rounding: requested %llu/%llu [+%llu], result %llu/%llu [+%llu]\n",
wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
wf_rounded.duty_length_ns, wf_rounded.period_length_ns, wf_rounded.duty_offset_ns);
@@ -382,7 +382,8 @@ static int __pwm_set_waveform(struct pwm_device *pwm,
wf_rounded.duty_length_ns, wf_rounded.period_length_ns, wf_rounded.duty_offset_ns,
wf_set.duty_length_ns, wf_set.period_length_ns, wf_set.duty_offset_ns);
}
- return 0;
+
+ return ret_tohw;
}

/**
--
2.39.5