Re: [PATCH v2] rtc: spacemit: handle regmap_test_bits() error return

Thank you for your contribution! Sashiko AI review found 1 potential issue(=
s) to consider:

Pre-existing issues:
- [High] The RTC time read retry loop in `p1_rtc_read_time` is vulnerable t=
o a torn read (time corruption) if a time roll-over occurs during the regis=
ter read.
--

--- Patch [1]: [PATCH v2] rtc: spacemit: handle regmap_test_bits() error re=
turn ---
commit a044092d776fab1e96ae2f8b48ace64aa0ab2325
Author: Surendra Singh Chouhan <[email protected]>

rtc: spacemit: handle regmap_test_bits() error return

p1_rtc_read_time() called if (!regmap_test_bits(regmap, RTC_CTRL, RTC_EN))
to check if the RTC was enabled. This evaluates negative error codes as
boolean false, causing read failures to be ignored. Fix this by capturing
the return value of regmap_test_bits() and returning the error code.

> diff --git a/drivers/rtc/rtc-spacemit-p1.c b/drivers/rtc/rtc-spacemit-p1.c
> index 43ab62494bb4b..1de7bd995d296 100644
> --- a/drivers/rtc/rtc-spacemit-p1.c
> +++ b/drivers/rtc/rtc-spacemit-p1.c
> @@ -57,8 +57,9 @@ static int p1_rtc_read_time(struct device *dev, struct =
rtc_time *t)
>  	u8 time[6];
>  	int ret;
> =20
> -	if (!regmap_test_bits(regmap, RTC_CTRL, RTC_EN))
> -		return -EINVAL;		/* RTC is disabled */
> +	ret =3D regmap_test_bits(regmap, RTC_CTRL, RTC_EN);
> +	if (ret <=3D 0)
> +		return ret ?: -EINVAL;	/* RTC is disabled or error */
> =20
>  	ret =3D regmap_bulk_read(regmap, RTC_TIME, time, sizeof(time));
>  	if (ret)
>  		return ret;
> =20
>  	do {
>  		seconds =3D time[0];
>  		ret =3D regmap_bulk_read(regmap, RTC_TIME, time, sizeof(time));
>  		if (ret)
>  			return ret;
>  	} while (time[0] !=3D seconds && --count);

[Severity: High]
This is a pre-existing issue, but does this loop correctly detect time
roll-overs that happen during the read?

If a time roll-over occurs during the second regmap_bulk_read() in
p1_rtc_read_time(), specifically after reading time[0] (seconds) but before
reading higher units, time[0] will match the seconds from the previous read.

This would cause the loop to terminate early and accept the newly read time
array.

Could this return a torn time from the RTC (for example, 14:00:59 instead of
13:59:59 or 14:00:00)?

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260724135803.8122=
[email protected]?part=3D1