Re: [PATCH v1 1/2] watchdog: dw_wdt: add stop watchdog operation

[Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

Hi Oleksij,

On Thu, 2017-09-14 at 10:14 +0200, Oleksij Rempel wrote:
> From: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> 
> The only way of stopping the watchdog is by resetting it.
> Add the watchdog op for stopping the device and reset if
> a reset line is provided.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Signed-off-by: Oleksij Rempel <o.rempel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Cc: Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
> Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> Cc: linux-watchdog-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ---
>  drivers/watchdog/dw_wdt.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 36be987ff9ef..50d8a6a5b5ac 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -135,6 +135,21 @@ static int dw_wdt_start(struct watchdog_device
> *wdd)
>  	return 0;
>  }
>  
> +static int dw_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
> +
> +	if (IS_ERR(dw_wdt->rst)) {

	if (!dw_wdt->rst) {

Since commit 65a3b6935d92 ("watchdog: dw_wdt: get reset lines from dt"),
the reset control is requested as optional, meaning dw_wdt->rst == NULL
if the reset line is not present. If an error is value is stored into
dw_wdt->rst, the probe function does not succeed.

> +		dev_warn(wdd->parent, "No reset line. Will not
> stop.\n");
> +		return PTR_ERR(dw_wdt->rst);
> +	}

regards
Philipp
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