Re: [PATCH v5 2/2] pwm: Add Nuvoton MA35D1 PWM controller support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The apply callback returns early when !state->enabled, dropping updates to polarity, period, and duty_cycle.
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--- Patch [2]: [PATCH v5 2/2] pwm: Add Nuvoton MA35D1 PWM controller support ---
commit cacbb01a99a86c07f6c67c4f1ef4d561c3481e94
Author: Chi-Wen Weng <cwweng@nuvoton.com>

pwm: Add Nuvoton MA35D1 PWM controller support

Adds a PWM framework driver for the Nuvoton MA35D1 EPWM controller.
The driver supports 6 PWM channels, utilizing up-counting, auto-reload,
and independent output modes.

> diff --git a/drivers/pwm/pwm-ma35d1.c b/drivers/pwm/pwm-ma35d1.c
> new file mode 100644
> index 0000000000000..4073cb72054a2
> --- /dev/null
> +++ b/drivers/pwm/pwm-ma35d1.c

[ ... ]

> +static int nuvoton_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			     const struct pwm_state *state)
> +{
> +	struct nuvoton_pwm *nvtpwm = nuvoton_pwm_from_chip(chip);
> +	unsigned int ch = pwm->hwpwm;
> +	u64 duty_cycles, period_cycles;
> +	u64 divisor;
> +	u32 cmpdat, period, prescale;
> +	int ret;
> +
> +	if (!state->enabled) {
> +		nuvoton_pwm_rmw(nvtpwm, MA35D1_REG_PWM_POEN,
> +				MA35D1_PWM_POEN_EN(ch), 0);
> +		nuvoton_pwm_rmw(nvtpwm, MA35D1_REG_PWM_CNTEN,
> +				MA35D1_PWM_CNTEN_EN(ch), 0);
> +
> +		return 0;
> +	}

[Severity: Medium]
Does this early return violate the PWM framework API contract by failing to
apply the full requested state?

If a consumer calls pwm_apply_state() with state->enabled = false but includes
updated polarity, period, or duty_cycle parameters, those changes appear to
be silently dropped because of this early return.

Since nuvoton_pwm_get_state() reads the configuration directly from hardware
registers, wouldn't subsequent state reads return stale values and desynchronize
the PWM core's cached state from the actual hardware configuration?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260721062308.536947-1-cwweng.linux@gmail.com?part=2