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

On 11/11/20 6:01 AM, Vaittinen, Matti wrote:

On Thu, 2020-11-05 at 13:38 +0200, Matti Vaittinen wrote:

quoted

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 <redacted>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---

//snip

quoted

+	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.

Yes. Good catch. Actually, since max_hw_heartbeat_ms is specified,
it can and should be a reasonable constant (like the usual 30 seconds).
It does not and should not be bound by max_hw_heartbeat_ms.

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...

No worries. Thanks for noticing.

Guenter

--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)