Re: [PATCH v1 3/3] rtc: rs5c372: support eco mode on R2223x

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The `rtc_r2223x` device is unhandled in the `RTC_VL_READ` and `RTC_VL_CLR` ioctls, causing incorrect voltage reporting and an inability to clear voltage warnings.
--

--- Patch [3]: [PATCH v1 3/3] rtc: rs5c372: support eco mode on R2223x ---
commit 03356cfada315a3baf4a319faaa5eba9b7ccba15
Author: Heiko Schocher <hs@nabladev.com>

rtc: rs5c372: support eco mode on R2223x
    
The R2223x can run in an eco mode that lowers its current consumption
from the backup supply. Enable it when ricoh,eco-mode property is
set in the device tree.

> diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
> index 30e272d650219..41d391bf07f7c 100644
> --- a/drivers/rtc/rtc-rs5c372.c
> +++ b/drivers/rtc/rtc-rs5c372.c

[ ... ]

> @@ -898,6 +917,13 @@ static int rs5c372_probe(struct i2c_client *client)
>  			rs5c372->time24 ? "24hr" : "am/pm"
>  			);
>  
> +	if (rs5c372->type == rtc_r2223x &&
> +	    device_property_read_bool(&client->dev, "ricoh,eco-mode")) {
> +		err = rs5c372_set_eco_mode(rs5c372, true);
> +		if (err < 0)
> +			return err;
> +	}
> +

[Severity: Medium]
Are we missing rtc_r2223x support in rs5c372_ioctl() for RTC_VL_READ and
RTC_VL_CLR?

For RTC_VL_READ, without rtc_r2223x in the switch statement, it falls through
to the default handler which misinterprets the PON bit (bit 4) as the
oscillator stopped (XSTP) bit, and ignores the voltage low (VDET) bit:

drivers/rtc/rtc-rs5c372.c:rs5c372_ioctl() {
    ...
		switch (rs5c->type) {
		case rtc_r2025sd:
		case rtc_r2221tl:
			// ... checks R2x2x_CTRL2_XSTP and R2x2x_CTRL2_VDET ...
			break;
		default:
			if (ctrl2 & RS5C_CTRL2_XSTP)
				flags |= RTC_VL_DATA_INVALID;
			break;
		}
    ...
}

Similarly, for RTC_VL_CLR, userspace cannot clear the voltage warning bit
because rtc_r2223x is omitted from the check:

drivers/rtc/rtc-rs5c372.c:rs5c372_ioctl() {
    ...
	case RTC_VL_CLR:
		/* clear VDET bit */
		if (rs5c->type == rtc_r2025sd || rs5c->type == rtc_r2221tl) {
			ctrl2 &= ~R2x2x_CTRL2_VDET;
    ...
}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260824110452.4038870-1-hs@nabladev.com?part=3