| Message ID | 20240619120920.2703605-4-claudiu.beznea.uj@bp.renesas.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | watchdog: rzg2l_wdt: Enable properly the watchdog clocks and power domain | expand |
On Wed, 19 Jun 2024 at 14:09, Claudiu <claudiu.beznea@tuxon.dev> wrote: > > From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> > > The rzg2l_wdt_restart() is called in atomic context. Calling > pm_runtime_{get_sync, resume_and_get}() or any other runtime PM resume > APIs is not an option as it may lead to issues as described in commit > e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'") > that removed the pm_runtime_get_sync() and enabled directly the clocks. > > Starting with RZ/G3S the watchdog could be part of its own > software-controlled power domain. In case the watchdog is not used the > power domain is off and accessing watchdog registers leads to aborts. > > To solve this, the patch powers on the power domain using > dev_pm_genpd_resume_restart_dev() API after enabling its clock. This is > not sleeping or taking any other locks as the watchdog power domain is not > registered with GENPD_FLAG_IRQ_SAFE flags. Would it be a problem to register the corresponding genpd using the GENPD_FLAG_IRQ_SAFE? Assuming it wouldn't, it looks like we should be able to make the watchdog device irq-safe too, by calling pm_runtime_irq_safe() during ->probe(). In that case it should be okay to call pm_runtime_get_sync() in atomic context, right? Kind regards Uffe > > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> > --- > drivers/watchdog/rzg2l_wdt.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c > index 6e3d7512f38c..bbdbbaa7b82b 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> > @@ -169,6 +170,17 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, > clk_enable(priv->pclk); > clk_enable(priv->osc_clk); > > + /* > + * The device may be part of a power domain that is currently > + * powered off. We need to power it on before accessing registers. > + * We don't undo the dev_pm_genpd_resume_restart_dev() as the device > + * need to be on for the reboot to happen. Also, as we are in atomic > + * context here, there is no need to increment PM runtime usage counter > + * (to make sure pm_runtime_active() doesn't return wrong code). > + */ > + if (!pm_runtime_active(wdev->parent)) > + dev_pm_genpd_resume_restart_dev(wdev->parent); > + > if (priv->devtype == WDT_RZG2L) { > ret = reset_control_deassert(priv->rstc); > if (ret) > -- > 2.39.2 >
Hi, Ulf, Sorry for the late reply, I was off last week. On 13.08.2024 16:56, Ulf Hansson wrote: > On Wed, 19 Jun 2024 at 14:09, Claudiu <claudiu.beznea@tuxon.dev> wrote: >> >> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> >> >> The rzg2l_wdt_restart() is called in atomic context. Calling >> pm_runtime_{get_sync, resume_and_get}() or any other runtime PM resume >> APIs is not an option as it may lead to issues as described in commit >> e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'") >> that removed the pm_runtime_get_sync() and enabled directly the clocks. >> >> Starting with RZ/G3S the watchdog could be part of its own >> software-controlled power domain. In case the watchdog is not used the >> power domain is off and accessing watchdog registers leads to aborts. >> >> To solve this, the patch powers on the power domain using >> dev_pm_genpd_resume_restart_dev() API after enabling its clock. This is >> not sleeping or taking any other locks as the watchdog power domain is not >> registered with GENPD_FLAG_IRQ_SAFE flags. > > Would it be a problem to register the corresponding genpd using the > GENPD_FLAG_IRQ_SAFE? Should be no problem, AFIK. > > Assuming it wouldn't, it looks like we should be able to make the > watchdog device irq-safe too, by calling pm_runtime_irq_safe() during > ->probe(). > > In that case it should be okay to call pm_runtime_get_sync() in atomic > context, right? Right! I registered the watchdog domain with GENPD_FLAG_IRQ_SAFE as well as it's parent domain (the always-on domain) and all looks good. However I need to run further testing to be sure nothing is broken. Thank you, Claudiu Beznea > > Kind regards > Uffe > >> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> >> --- >> drivers/watchdog/rzg2l_wdt.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c >> index 6e3d7512f38c..bbdbbaa7b82b 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> >> @@ -169,6 +170,17 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, >> clk_enable(priv->pclk); >> clk_enable(priv->osc_clk); >> >> + /* >> + * The device may be part of a power domain that is currently >> + * powered off. We need to power it on before accessing registers. >> + * We don't undo the dev_pm_genpd_resume_restart_dev() as the device >> + * need to be on for the reboot to happen. Also, as we are in atomic >> + * context here, there is no need to increment PM runtime usage counter >> + * (to make sure pm_runtime_active() doesn't return wrong code). >> + */ >> + if (!pm_runtime_active(wdev->parent)) >> + dev_pm_genpd_resume_restart_dev(wdev->parent); >> + >> if (priv->devtype == WDT_RZG2L) { >> ret = reset_control_deassert(priv->rstc); >> if (ret) >> -- >> 2.39.2 >>
diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c index 6e3d7512f38c..bbdbbaa7b82b 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> @@ -169,6 +170,17 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, clk_enable(priv->pclk); clk_enable(priv->osc_clk); + /* + * The device may be part of a power domain that is currently + * powered off. We need to power it on before accessing registers. + * We don't undo the dev_pm_genpd_resume_restart_dev() as the device + * need to be on for the reboot to happen. Also, as we are in atomic + * context here, there is no need to increment PM runtime usage counter + * (to make sure pm_runtime_active() doesn't return wrong code). + */ + if (!pm_runtime_active(wdev->parent)) + dev_pm_genpd_resume_restart_dev(wdev->parent); + if (priv->devtype == WDT_RZG2L) { ret = reset_control_deassert(priv->rstc); if (ret)