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Message-ID: <a5a807c1-76ef-4cf7-a2cf-bc432c420ded@roeck-us.net>
Date: Mon, 22 Jan 2024 09:39:27 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Claudiu <claudiu.beznea@...on.dev>, wim@...ux-watchdog.org,
robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
geert+renesas@...der.be, magnus.damm@...il.com, mturquette@...libre.com,
sboyd@...nel.org, p.zabel@...gutronix.de, biju.das.jz@...renesas.com
Cc: linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-clk@...r.kernel.org, Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 07/10] watchdog: rzg2l_wdt: Add suspend/resume support
On 1/22/24 03:11, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>
> The RZ/G3S supports deep sleep states where power to most of the IP blocks
> is cut off. To ensure proper working of the watchdog when resuming from
> such states, the suspend function is stopping the watchdog and the resume
> function is starting it. There is no need to configure the watchdog
> in case the watchdog was stopped prior to starting suspend.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
> drivers/watchdog/rzg2l_wdt.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 9333dc1a75ab..186796b739f7 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -279,6 +279,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
> priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
>
> watchdog_set_drvdata(&priv->wdev, priv);
> + dev_set_drvdata(dev, priv);
> ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev);
> if (ret)
> return ret;
> @@ -300,10 +301,35 @@ static const struct of_device_id rzg2l_wdt_ids[] = {
> };
> MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
>
> +static int rzg2l_wdt_suspend_late(struct device *dev)
> +{
> + struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
> +
> + if (!watchdog_active(&priv->wdev))
> + return 0;
> +
> + return rzg2l_wdt_stop(&priv->wdev);
> +}
> +
> +static int rzg2l_wdt_resume_early(struct device *dev)
> +{
> + struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
> +
> + if (!watchdog_active(&priv->wdev))
> + return 0;
> +
> + return rzg2l_wdt_start(&priv->wdev);
> +}
> +
> +static const struct dev_pm_ops rzg2l_wdt_pm_ops = {
> + LATE_SYSTEM_SLEEP_PM_OPS(rzg2l_wdt_suspend_late, rzg2l_wdt_resume_early)
> +};
> +
> static struct platform_driver rzg2l_wdt_driver = {
> .driver = {
> .name = "rzg2l_wdt",
> .of_match_table = rzg2l_wdt_ids,
> + .pm = pm_ptr(&rzg2l_wdt_pm_ops),
I think this will create a build error if CONFIG_PM=n because rzg2l_wdt_pm_ops
will be unused but is not marked with __maybe_unused. But then the driver won't be
operational with CONFIG_PM=n, so I really wonder if it makes sense to include any
such conditional code instead of making the driver depend on CONFIG_PM.
I really don't think it is desirable to suggest that the driver would work with
CONFIG_PM=n if that isn't really true.
Guenter
> },
> .probe = rzg2l_wdt_probe,
> };
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