Hi Fabrizio,
On Thu, Mar 1, 2018 at 7:17 PM, Fabrizio Castro
<fabrizio.castro@xxxxxxxxxxxxxx> wrote:
> On R-Car Gen2 and RZ/G1 the watchdog IP clock needs to be always ON,
> on R-Car Gen3 we power the IP down during suspend.
>
> This commit adds suspend/resume support, so that the watchdog counting
> "pauses" during suspend on all of the SoCs compatible with this driver
> and on those we are now adding support for (R-Car Gen2 and RZ/G1).
>
> Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@xxxxxxxxxxxxxx>
> ---
> v6->v7:
> * backup and restore register RWTCNT instead of using rwdt_get_timeleft and
> rwdt_set_timeleft
Thanks for the update (v6 and v7)!
>
> drivers/watchdog/renesas_wdt.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> index 831ef83..024d54e 100644
> --- a/drivers/watchdog/renesas_wdt.c
> +++ b/drivers/watchdog/renesas_wdt.c
> @@ -49,6 +49,7 @@ struct rwdt_priv {
> void __iomem *base;
> struct watchdog_device wdev;
> unsigned long clk_rate;
> + u16 time_left;
> u8 cks;
> };
>
> @@ -203,6 +204,30 @@ static int rwdt_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static int __maybe_unused rwdt_suspend(struct device *dev)
> +{
> + struct rwdt_priv *priv = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&priv->wdev)) {
> + priv->time_left = readw(priv->base + RWTCNT);
> + rwdt_stop(&priv->wdev);
> + }
> + return 0;
> +}
> +
> +static int __maybe_unused rwdt_resume(struct device *dev)
> +{
> + struct rwdt_priv *priv = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&priv->wdev)) {
> + rwdt_start(&priv->wdev);
> + rwdt_write(priv, priv->time_left, RWTCNT);
Upon given it more thought, I'm a bit worried about restoring the
original time left.
In my experiments, it may take a few seconds before userspace fully resumes.
If time_left was a small value, the system may reboot before userspace has
a chance to send its next ping.
This was with NFS root, so heavily impacted by the delays introduced by the
PHY link getting up again.
So just using rwdt_stop()/rwdt_start() may be the safest option.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
