linux-kernel - Re: [PATCH 4/4] watchdog: sama5d4: Add comment explaining what happens on resume

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Message-ID: <d97f8e83-7fdd-61e5-01c9-af089f92b71d@roeck-us.net>
Date:   Sat, 4 Mar 2017 07:07:28 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Wim Van Sebroeck <wim@...ana.be>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Wenyou.Yang@...rochip.com, linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] watchdog: sama5d4: Add comment explaining what
 happens on resume

On 03/02/2017 09:31 AM, Alexandre Belloni wrote:
> Because suspending to RAM may lose the register values, they are restored
> on resume. This is currently done unconditionally because there is
> currently no way to know (from the driver) whether they have really been
> lost or are still valid. Writing MR also pings the watchdog and this may
> not be what is expected so add a comment explaining why it happens.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

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

> ---
>  drivers/watchdog/sama5d4_wdt.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index d710014f3b7d..0ae947c3d7bc 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -300,6 +300,11 @@ static int sama5d4_wdt_resume(struct device *dev)
>  {
>  	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
>
> +	/*
> +	 * FIXME: writing MR also pings the watchdog which may not be desired.
> +	 * This should only be done when the registers are lost on suspend but
> +	 * there is no way to get this information right now.
> +	 */
>  	sama5d4_wdt_init(wdt);
>
>  	return 0;
>