Hi Claudiu,
Thanks for the feedback.
> -----Original Message-----
> From: Claudiu <claudiu.beznea@xxxxxxxxx>
> Sent: Monday, August 26, 2024 4:25 PM
> Subject: [PATCH 3/3] watchdog: rzg2l_wdt: Power on the watchdog domain in the restart handler
>
> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>
> On RZ/G3S the watchdog can be part of a software-controlled PM domain. In this case, the watchdog
> device need to be powered on in struct watchdog_ops::restart API. This can be done though
> pm_runtime_resume_and_get() API if the watchdog PM domain and watchdog device are marked as IRQ safe.
> We mark the watchdog PM domain as IRQ safe with GENPD_FLAG_IRQ_SAFE when the watchdog PM domain is
> registered and the watchdog device though pm_runtime_irq_safe().
>
> Before commit e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait
> context'") pm_runtime_get_sync() was used in watchdog restart handler (which is similar to
> pm_runtime_resume_and_get() except the later one handles the runtime resume errors).
>
> Commit e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait
> context'") dropped the pm_runtime_get_sync() and replaced it with
> clk_prepare_enable() to avoid invalid wait context due to genpd_lock() in genpd_runtime_resume() being
> called from atomic context. But
> clk_prepare_enable() doesn't fit for this either (as reported by Ulf Hansson) as clk_prepare() can
> also sleep (it just not throw invalid wait context warning as it is not written for this).
>
> Because the watchdog device is marked now as IRQ safe (though this patch) the
> irq_safe_dev_in_sleep_domain() call from genpd_runtime_resume() returns
> 1 for devices not registering an IRQ safe PM domain for watchdog (as the watchdog device is IRQ safe,
> PM domain is not and watchdog PM domain is always-on), this being the case of RZ/G2 devices that uses
RZ/G2L alike devices or be specific RZ/{G2L,G2LC,G2UL,V2L} as it is not applicable for
RZ/G2{H,M,N,E}devices.
> this driver, we can now drop also the clk_prepare_enable() calls in restart handler and rely on
> pm_runtime_resume_and_get().
>
> Thus, drop clk_prepare_enable() and use pm_runtime_resume_and_get() in watchdog restart handler.
Can this patch be fix for Commit e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait
> context'") on RZ/{G2L,G2LC,G2UL,V2L} SoC??
Cheers,
Biju
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> ---
> drivers/watchdog/rzg2l_wdt.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c index
> 2a35f890a288..e9e0408c96f7 100644
> --- a/drivers/watchdog/rzg2l_wdt.c
> +++ b/drivers/watchdog/rzg2l_wdt.c
> @@ -12,6 +12,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> #include <linux/pm_runtime.h>
> #include <linux/reset.h>
> #include <linux/units.h>
> @@ -166,8 +167,23 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
> struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> int ret;
>
> - clk_prepare_enable(priv->pclk);
> - clk_prepare_enable(priv->osc_clk);
> + /*
> + * In case of RZ/G3S the watchdog device may be part of an IRQ safe power
> + * domain that is currently powered off. In this case we need to power
> + * it on before accessing registers. Along with this the clocks will be
> + * enabled. We don't undo the pm_runtime_resume_and_get() as the device
> + * need to be on for the reboot to happen.
> + *
> + * For the rest of RZ/G2 devices (and for RZ/G3S with old device trees
> + * where PM domains are registered like on RZ/G2 devices) it is safe
> + * to call pm_runtime_resume_and_get() as the
> + * irq_safe_dev_in_sleep_domain() call in genpd_runtime_resume()
> + * returns non zero value and the genpd_lock() is avoided, thus, there
> + * will be no invalid wait context reported by lockdep.
> + */
> + ret = pm_runtime_resume_and_get(wdev->parent);
> + if (ret)
> + return ret;
>
> if (priv->devtype == WDT_RZG2L) {
> ret = reset_control_deassert(priv->rstc);
> @@ -275,6 +291,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>
> priv->devtype = (uintptr_t)of_device_get_match_data(dev);
>
> + pm_runtime_irq_safe(&pdev->dev);
> pm_runtime_enable(&pdev->dev);
>
> priv->wdev.info = &rzg2l_wdt_ident;
> --
> 2.39.2
>
