Re: [PATCH RFC v2 7/9] watchdog: rzv2h: Add syscon support for RZ/T2H and RZ/N2H WDT control register

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The error rollback path in `rzv2h_wdt_stop()` leaves the watchdog deasserted but unconfigured, breaking the hardware state machine and potentially causing spurious resets.
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commit e9173a2a019341cec05cdc87e042bd8dd2f92721
Author: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

watchdog: rzv2h: Add syscon support for RZ/T2H and RZ/N2H WDT control register

On RZ/T2H and RZ/N2H SoCs, the WDTDCR register is shared and managed by a
dedicated SYS driver. This commit updates the WDT driver to support a syscon
regmap interface for WDTDCR control while maintaining backward compatibility
with direct mapping.

> diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
> index e9545b8f5fd09..e14ff853a4e9f 100644
> --- a/drivers/watchdog/rzv2h_wdt.c
> +++ b/drivers/watchdog/rzv2h_wdt.c

[ ... ]

> @@ -179,8 +208,13 @@ static int rzv2h_wdt_stop(struct watchdog_device *wdev)
>  	if (ret)
>  		return ret;
>  
> -	if (priv->of_data->wdtdcr)
> -		rzt2h_wdt_wdtdcr_count_stop(priv);
> +	if (priv->of_data->wdtdcr) {
> +		ret = rzt2h_wdt_wdtdcr_count_stop(priv);
> +		if (ret) {
> +			reset_control_deassert(priv->rstc);
> +			return ret;
> +		}
> +	}

[Severity: High]
When rzt2h_wdt_wdtdcr_count_stop() fails, this rollback path deasserts the
reset line and returns an error without reconfiguring the hardware.

Because rzv2h_wdt_stop() returns an error, the watchdog subsystem will keep
the device marked as active and continue pinging it via rzv2h_wdt_ping().

Since the earlier reset_control_assert() wiped the configuration registers,
will the subsequent ping lock the unconfigured control registers and
potentially cause an immediate spurious system reset?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260702123112.161160-1-prabhakar.mahadev-lad.rj@bp.renesas.com?part=7