RE: [PATCH 1/4] watchdog: da9063: Add restart handler support

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On 09 December 2014 11:23 Geert Uytterhoeven wrote:

Hi Geert,

> Subject: [PATCH 1/4] watchdog: da9063: Add restart handler support
> 
> Register a restart handler for the da9063 watchdog.  System restart is
> triggered by sending the shutdown command to the PMIC.
> As more-suitable restart handlers may exist, the priority of the
> watchdog restart handler is set to 128.
> 
> The actual restart method was inspired by a platform-specific patch from
> the BSP by Hisashi Nakamura <hisashi.nakamura.ak@xxxxxxxxxxx>.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> Tested on r8a7791/koelsch
> ---

[...]

+static int da9063_wdt_restart_handler(struct notifier_block *this,
+				      unsigned long mode, void *cmd)
+{
+	struct da9063_watchdog *wdt = container_of(this,
+						   struct da9063_watchdog,
+						   restart_handler);
+	int ret;
+
+	ret = regmap_write(wdt->da9063->regmap, DA9063_REG_CONTROL_F,
+			   DA9063_SHUTDOWN);

I am stating the obvious here.

DA9063_REG_CONTROL_F, DA9063_SHUTDOWN will cause the sequencer to
power down to RESET Mode -- which means if this I2C command succeeds 
there will be a sudden loss of power and any unsaved information will be 
lost after this point.

This is exactly how I have done it in the past.

+	if (ret)
+		dev_alert(wdt->da9063->dev, "Failed to shutdown (err = %d)\n",
+			  ret);
+
+	return NOTIFY_DONE;
+}
+

[...]

>  static const struct watchdog_info da9063_watchdog_info = {
>  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
>  	.identity = "DA9063 Watchdog",
> @@ -163,14 +182,25 @@ static int da9063_wdt_probe(struct
> platform_device *pdev)
>  	dev_set_drvdata(&pdev->dev, wdt);
> 
>  	ret = watchdog_register_device(&wdt->wdtdev);
> +	if (ret)
> +		return ret;
> 
> -	return ret;
> +	wdt->restart_handler.notifier_call = da9063_wdt_restart_handler;
> +	wdt->restart_handler.priority = 128;
> +	ret = register_restart_handler(&wdt->restart_handler);
> +	if (ret)
> +		dev_err(wdt->da9063->dev,
> +			"Failed to register restart handler (err = %d)\n", ret);

 (I guess this is intentional).. if the restart handler doesn't get registered then
this problem is just ignored and not counted as a real error.

> +
> +	return 0;
>  }
> 
>  static int da9063_wdt_remove(struct platform_device *pdev)
>  {
>  	struct da9063_watchdog *wdt = dev_get_drvdata(&pdev->dev);
> 
> +	unregister_restart_handler(&wdt->restart_handler);
> +
>  	watchdog_unregister_device(&wdt->wdtdev);
> 
>  	return 0;

Despite the above, these are just my comments.
It all looks fine to me.

Acked-by: Steve Twiss <stwiss.opensource@xxxxxxxxxxx>

Regards,
Steve
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