Re: [PATCH 2/7] gpiolib: regmap: add GPIO_REGMAP_QUIRK_SET_AFTER_DIR

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] gpio: regmap: missing return value check for gpio_regmap_set in direction_output
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commit 4dfbff55c3fbea74424f90710c5b76efb22f738e
Author: Long Zhao <longzhao@ambarella.com>

gpiolib: regmap: add GPIO_REGMAP_QUIRK_SET_AFTER_DIR

Some controllers ignore output writes while a line is still an input.
Add a behaviour flag so the output value is written after the direction
change. This is a legacy quirk. New hardware must not use it.

> diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> index 51b4d69b87403..0a44deae3d01e 100644
> --- a/drivers/gpio/gpio-regmap.c
> +++ b/drivers/gpio/gpio-regmap.c

[ ... ]

> @@ -271,9 +272,17 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
>  			return ret;
>  	}
>  
> -	gpio_regmap_set(chip, offset, value);
> +	if (!(gpio->quirks & GPIO_REGMAP_QUIRK_SET_AFTER_DIR))
> +		gpio_regmap_set(chip, offset, value);
>  
> -	return gpio_regmap_set_direction(chip, offset, true);
> +	ret = gpio_regmap_set_direction(chip, offset, true);
> +	if (ret)
> +		return ret;
> +
> +	if (gpio->quirks & GPIO_REGMAP_QUIRK_SET_AFTER_DIR)
> +		gpio_regmap_set(chip, offset, value);
> +
> +	return 0;
>  }

[Severity: Medium]
Does this code silently ignore hardware or bus errors?

If gpio_regmap_set() fails due to an underlying I2C/SPI bus timeout or NACK,
it returns a negative error code. However, the return value is dropped in the
newly added GPIO_REGMAP_QUIRK_SET_AFTER_DIR path, just as it is in the
pre-existing path.

Could this falsely signal to the gpiolib framework that the output pin was
successfully configured, leaving the hardware in an undefined state and
masking the error from consumers?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261009-cv75-gpio-v1-0-5836bd438423@ambarella.com?part=2