Re: [PATCH v7 3/8] watchdog: rzv2h: Drop enabling clocks in the restart handler

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] watchdog: unintended system reset during suspend due to permanently enabled clocks
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commit 465743d35253a3a281f9ce8cea373ed0c3ae3e5a
Author: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

watchdog: rzv2h: Drop enabling clocks in the restart handler
    
The commit drops dynamic clock enable/disable operations from the watchdog
restart handler to avoid deadlocking on the clock framework's global
enable_lock. Instead, it keeps the peripheral and oscillator clocks enabled
for the lifetime of the device using devm_clk_get_enabled() and
devm_clk_get_optional_enabled().

> diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
> index f247e42d54f54..55ac11fcfcabd 100644
> --- a/drivers/watchdog/rzv2h_wdt.c
> +++ b/drivers/watchdog/rzv2h_wdt.c

[ ... ]

> @@ -292,11 +279,11 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
>  	if (IS_ERR(priv->base))
>  		return PTR_ERR(priv->base);
>  
> -	priv->pclk = devm_clk_get_prepared(dev, "pclk");
> +	priv->pclk = devm_clk_get_enabled(dev, "pclk");
>  	if (IS_ERR(priv->pclk))
>  		return dev_err_probe(dev, PTR_ERR(priv->pclk), "Failed to get pclk\n");
>  
> -	priv->oscclk = devm_clk_get_optional_prepared(dev, "oscclk");
> +	priv->oscclk = devm_clk_get_optional_enabled(dev, "oscclk");

[Severity: High]
Does switching to devm_clk_get_enabled() and devm_clk_get_optional_enabled()
prevent the PM framework from fully gating these clocks during suspend?

By permanently incrementing the CCF enable_count by 1 here in probe, it appears
that pm_clk_suspend() will only drop the count from 2 to 1 during system
suspend, leaving the clocks physically enabled.

If the clocks remain running while the system is suspended and the ping worker
is frozen, won't the hardware watchdog counter inevitably underflow and trigger
an unintended system reset?

>  	if (IS_ERR(priv->oscclk))
>  		return dev_err_probe(dev, PTR_ERR(priv->oscclk), "Failed to get oscclk\n");
>

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Sashiko AI review · https://sashiko.dev/#/patchset/20260929105021.542730-1-prabhakar.mahadev-lad.rj@bp.renesas.com?part=3