linux-kernel - Re: [PATCH v5 3/4] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

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Date:   Wed, 11 Nov 2020 14:01:32 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "mazziesaccount@...il.com" <mazziesaccount@...il.com>
CC:     "linux@...ck-us.net" <linux@...ck-us.net>,
        "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-power <linux-power@...rohmeurope.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
Subject: Re: [PATCH v5 3/4] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

On Thu, 2020-11-05 at 13:38 +0200, Matti Vaittinen wrote:
> Add Watchdog support for ROHM BD9576MUF and BD9573MUF PMICs which are
> mainly used to power the R-Car series processors. The watchdog is
> pinged using a GPIO and enabled using another GPIO. Additionally
> watchdog time-out can be configured to HW prior starting the
> watchdog.
> Watchdog timeout can be configured to detect only delayed ping or in
> a window mode where also too fast pings are detected.
> 
> Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> 

//snip

> +	ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-
> ms",
> +						  &hw_margin[0], 1, 2);
> +	if (ret < 0 && ret != -EINVAL)
> +		return ret;
> +
> +	if (ret == 1)
> +		hw_margin_max = hw_margin[0];
> +
> +	if (ret == 2) {
> +		hw_margin_max = hw_margin[1];
> +		hw_margin_min = hw_margin[0];
> +	}
> +
> +	ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
> +	if (ret)
> +		return ret;
> +
> +	priv->always_running = of_property_read_bool(np, "always-
> running");
> +
> +	watchdog_set_drvdata(&priv->wdd, priv);
> +
> +	priv->wdd.info			= &bd957x_wdt_ident;
> +	priv->wdd.ops			= &bd957x_wdt_ops;
> +	priv->wdd.min_hw_heartbeat_ms	= hw_margin_min;
> +	priv->wdd.max_hw_heartbeat_ms	= hw_margin_max;
> +	priv->wdd.parent		= dev;
> +	priv->wdd.timeout		= (hw_margin_max / 2) * 1000;

Hmm. Just noticed this value does not make sense, right?
Maximum hw_margin is 4416 ms. If I read this correctly timeout should
be in seconds -  so result is around 2 000 000 seconds here. I think it
is useless value...

Perhaps
	priv->wdd.timeout		= (hw_margin_max / 2) / 1000;
	if (!priv->wdd.timeout)
		priv->wdd.timeout = 1;
would be more appropriate.

I need to do some testing when I get the HW at my hands - please don't
apply this patch just yet. I will respin this after some testing - or
if other patches are applied then I will just send this one alone.

Sorry for the hassle...

--Matti

--
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~

Simon says - in Latin please.
"non cogito me" dixit Rene Descarte, deinde evanescavit

(Thanks for the translation Simon)