6.12-stable review patch. If anyone has any objections, please let me know.
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From: Uwe Kleine-König u.kleine-koenig@baylibre.com
[ Upstream commit b2eaa1170e45dc18eb09dcc9abafbe9a7502e960 ]
Some PWM hardwares (e.g. MC33XS2410) cannot implement a zero duty cycle but can instead disable the hardware which also results in a constant inactive output.
There are some checks (enabled with CONFIG_PWM_DEBUG) to help implementing a driver without violating the normal rounding rules. Make them less strict to let above described hardware pass without warning.
Reported-by: Dimitri Fedrau dima.fedrau@gmail.com Link: https://lore.kernel.org/r/20241103205215.GA509903@debian Fixes: 3ad1f3a33286 ("pwm: Implement some checks for lowlevel drivers") Signed-off-by: Uwe Kleine-König u.kleine-koenig@baylibre.com Reviewed-by: Dimitri Fedrau dima.fedrau@gmail.com Tested-by: Dimitri Fedrau dima.fedrau@gmail.com Link: https://lore.kernel.org/r/20241105153521.1001864-2-u.kleine-koenig@baylibre.... Signed-off-by: Uwe Kleine-König ukleinek@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 6e752e148b98c..210368099a064 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -75,7 +75,7 @@ static void pwm_apply_debug(struct pwm_device *pwm, state->duty_cycle < state->period) dev_warn(pwmchip_parent(chip), ".apply ignored .polarity\n");
- if (state->enabled && + if (state->enabled && s2.enabled && last->polarity == state->polarity && last->period > s2.period && last->period <= state->period) @@ -83,7 +83,11 @@ static void pwm_apply_debug(struct pwm_device *pwm, ".apply didn't pick the best available period (requested: %llu, applied: %llu, possible: %llu)\n", state->period, s2.period, last->period);
- if (state->enabled && state->period < s2.period) + /* + * Rounding period up is fine only if duty_cycle is 0 then, because a + * flat line doesn't have a characteristic period. + */ + if (state->enabled && s2.enabled && state->period < s2.period && s2.duty_cycle) dev_warn(pwmchip_parent(chip), ".apply is supposed to round down period (requested: %llu, applied: %llu)\n", state->period, s2.period); @@ -99,7 +103,7 @@ static void pwm_apply_debug(struct pwm_device *pwm, s2.duty_cycle, s2.period, last->duty_cycle, last->period);
- if (state->enabled && state->duty_cycle < s2.duty_cycle) + if (state->enabled && s2.enabled && state->duty_cycle < s2.duty_cycle) dev_warn(pwmchip_parent(chip), ".apply is supposed to round down duty_cycle (requested: %llu/%llu, applied: %llu/%llu)\n", state->duty_cycle, state->period,