linux-kernel - Re: [PATCH v1] watchdog: wdat: add param. to start wdog on module insertion

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Date:   Fri, 19 Feb 2021 12:54:47 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Flavio Suligoi <f.suligoi@...m.it>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] watchdog: wdat: add param. to start wdog on module
 insertion

Hi,

On Thu, Feb 18, 2021 at 05:32:00PM +0100, Flavio Suligoi wrote:
> Add the parameter "start_enable" to start the watchdog
> directly on module insertion.
> 
> In an embedded system, for some applications, the watchdog
> must be activated as soon as possible.
> 
> In some embedded x86 boards the watchdog can be activated
> directly by the BIOS (with an appropriate setting of the
> BIOS setup). In other cases, when this BIOS feature is not
> present, the possibility to start the watchdog immediately
> after the module loading can be very useful.
> 
> Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>
> ---
>  drivers/watchdog/wdat_wdt.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/watchdog/wdat_wdt.c b/drivers/watchdog/wdat_wdt.c
> index cec7917790e5..b990d0197d2e 100644
> --- a/drivers/watchdog/wdat_wdt.c
> +++ b/drivers/watchdog/wdat_wdt.c
> @@ -61,6 +61,12 @@ module_param(timeout, int, 0);
>  MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
>  		 __MODULE_STRING(WDAT_DEFAULT_TIMEOUT) ")");
>  
> +#define START_DEFAULT	0
> +static int start_enabled = START_DEFAULT;
> +module_param(start_enabled, int, 0);
> +MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "
> +		 "(default=" __MODULE_STRING(START_DEFAULT) ")");
> +
>  static int wdat_wdt_read(struct wdat_wdt *wdat,
>  	 const struct wdat_instruction *instr, u32 *value)
>  {
> @@ -437,6 +443,8 @@ static int wdat_wdt_probe(struct platform_device *pdev)
>  	}
>  
>  	wdat_wdt_boot_status(wdat);
> +	if (start_enabled)
> +		wdat_wdt_start(&wdat->wdd);

No objections to this if it is really needed. However, I think it is
better start the watchdog after devm_watchdog_register_device() has been
called so we have everything initialized.

>  	wdat_wdt_set_running(wdat);
>  
>  	ret = wdat_wdt_enable_reboot(wdat);
> -- 
> 2.25.1