Re: [hwmon PATCH v3 6/6] hwmon: (adt7470) Use cached PWM frequency value

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Incorrect PWM frequency is cached in `pwm1_freq_set()` for high frequencies.
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--- Patch [6]: [hwmon PATCH v3 6/6] hwmon: (adt7470) Use cached PWM frequency value ---
commit 1d5eabde22a3c2244581f951eb2060da34244bbe
Author: Luiz Angelo Daros de Luca <[email protected]>

hwmon: (adt7470) Use cached PWM frequency value

This commit updates the driver to use a cached PWM frequency in the read
path instead of querying the hardware. It aims to prevent exposing negative
error codes through sysfs if the register read fails.

> diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
> index f1150f0fe2172..405eda900650f 100644
> --- a/drivers/hwmon/adt7470.c
> +++ b/drivers/hwmon/adt7470.c

[ ... ]

> @@ -817,6 +818,10 @@ static int pwm1_freq_set(struct device *dev, long freq)
>  	err = regmap_update_bits(data->regmap, ADT7470_REG_CFG_2,
>  				 ADT7470_FREQ_MASK,
>  				 index << ADT7470_FREQ_SHIFT);
> +	if (err < 0)
> +		goto out;
> +
> +	data->pwm_freq = adt7470_freq_map[index];

[Severity: Medium]
Is the correct index used for caching the frequency here?

Looking at pwm1_freq_set(), when setting a high frequency like 1400Hz or 
22500Hz, the initial index is resolved to 8 or 9. The code then modifies 
this by subtracting 8 (index -= 8) before updating the hardware registers.

By using this modified index to update data->pwm_freq, does the driver end
up caching 11Hz or 15Hz (indexes 0 and 1) instead of the requested high
frequency?

>  out:
>  	mutex_unlock(&data->lock);
>

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=6