linux-kernel - Re: [PATCHv2] watchdog: qcom: Add suspend/resume support

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Date:   Thu, 17 Jan 2019 10:37:07 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Guenter Roeck <groeck@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-watchdog@...r.kernel.org
Cc:     Rajendra Nayak <rnayak@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Doug Anderson <dianders@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: Re: [PATCHv2] watchdog: qcom: Add suspend/resume support

Quoting Sai Prakash Ranjan (2019-01-17 07:19:42)
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index 780971318810..5dfd604477a4 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -245,6 +245,28 @@ static int qcom_wdt_remove(struct platform_device *pdev)
>         return 0;
>  }
>  
> +static int __maybe_unused qcom_wdt_suspend(struct device *dev)
> +{
> +       struct qcom_wdt *wdt = dev_get_drvdata(dev);
> +
> +       if (watchdog_active(&wdt->wdd))
> +               qcom_wdt_stop(&wdt->wdd);
> +
> +       return 0;
> +}
> +
> +static int __maybe_unused qcom_wdt_resume(struct device *dev)
> +{
> +       struct qcom_wdt *wdt = dev_get_drvdata(dev);
> +
> +       if (watchdog_active(&wdt->wdd))
> +               qcom_wdt_start(&wdt->wdd);
> +
> +       return 0;
> +}

This looks fairly generic. For example, the Mediatek driver also stops
and starts (but also pings after starting). Grepping for 'active' in
drivers/watchdog/ finds more examples. Could there be some functions in
watchdog core that do the common things like watchdog_stop() and
watchdog_start() and watchdog_start_and_ping()? Or maybe a bit can be
set during registration so that the 'struct class watchdog_class' can
get PM ops to stop and start on suspend/resume of the watchdog character
device?

Nothing is wrong with the patch, I'm just bemoaning the amount of code
duplication here.