[PATCH v2 0/3] watchdog: rzg2l_wdt: Enable properly the watchdog clocks and power domain

[PATCH v2 0/3] watchdog: rzg2l_wdt: Enable properly the watchdog clocks and power domain

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Hi,

Watchdog device available on RZ/G3S SoC is part of a software-controlled
power domain. The watchdog driver implements struct
watchdog_ops::restart() handler which is called in atomic context via
this call chain:

kernel_restart() ->
  machine_restart() ->
    do_kernel_restart() ->
      atomic_notifier_call_chain() ->
        watchdog_restart_notifier()
          rzg2l_wdt_restart()

When the rzg2l_wdt_restart() is called it may happen that the watchdog
clocks to be disabled and the associated power domain to be off.
Accessing watchdog registers in this state leads to aborts and system
blocks.

To solve this issue the watchdog power domain was marked as IRQ safe
as well as watchdog device (as proposed by Ulf Hansson). Along with
it the clk_prepare_enable() calls from the watchdog restart() handler
were removed and all is based now on pm_runtime_resume_and_get()
as explained in patch 03/03.

Series contains also power domain driver changes to be able to
register the watchdog PM domain as an IRQ safe one.

Initial RFC series for solving this issue was posted at [1].

It is safe to merge watchdog and PM domain driver changes though
different trees.

Thank you,
Claudiu Beznea

[1] https://lore.kernel.org/all/20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com/

Changes in v2:
- adjusted patch title for patch 02/03
- adjusted description for patch 03/03 along with comment
  from code

Changes since RFC:
- dropped patches 01/03, 02/03 from RFC
- adjusted power domain driver to be able to register the
  watchdog PM domain as an IRQ safe one
- drop clock prepare approach from watchdog driver presented in RFC
  and rely only on pm_runtime_resume_and_get()
- mark the watchdog device as IRQ safe

Claudiu Beznea (3):
  clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones
  clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as
    IRQ safe
  watchdog: rzg2l_wdt: Power on the watchdog domain in the restart
    handler

 drivers/clk/renesas/r9a08g045-cpg.c | 43 ++++++++++++-----------------
 drivers/clk/renesas/rzg2l-cpg.c     | 13 +++++----
 drivers/clk/renesas/rzg2l-cpg.h     | 10 ++-----
 drivers/watchdog/rzg2l_wdt.c        | 20 ++++++++++++--
 4 files changed, 46 insertions(+), 40 deletions(-)

-- 
2.39.2

[PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
to be able to power on the watchdog PM domain from atomic context. For
this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
for individual PM domains.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v2:
- none

Changes since RFC:
- none; this patch is new

 drivers/clk/renesas/r9a08g045-cpg.c | 44 +++++++++++------------------
 drivers/clk/renesas/rzg2l-cpg.c     | 13 +++++----
 drivers/clk/renesas/rzg2l-cpg.h     | 10 ++-----
 3 files changed, 28 insertions(+), 39 deletions(-)

diff --git a/drivers/clk/renesas/r9a08g045-cpg.c b/drivers/clk/renesas/r9a08g045-cpg.c
index 213499fc8fb5..ec0672651fe0 100644
--- a/drivers/clk/renesas/r9a08g045-cpg.c
+++ b/drivers/clk/renesas/r9a08g045-cpg.c
@@ -9,6 +9,7 @@
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/pm_domain.h>
 
 #include <dt-bindings/clock/r9a08g045-cpg.h>
 
@@ -258,52 +259,41 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
 	/* Keep always-on domain on the first position for proper domains registration. */
 	DEF_PD("always-on",	R9A08G045_PD_ALWAYS_ON,
 				DEF_REG_CONF(0, 0),
-				RZG2L_PD_F_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON),
 	DEF_PD("gic",		R9A08G045_PD_GIC,
 				DEF_REG_CONF(CPG_BUS_ACPU_MSTOP, BIT(3)),
-				RZG2L_PD_F_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON),
 	DEF_PD("ia55",		R9A08G045_PD_IA55,
 				DEF_REG_CONF(CPG_BUS_PERI_CPU_MSTOP, BIT(13)),
-				RZG2L_PD_F_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON),
 	DEF_PD("dmac",		R9A08G045_PD_DMAC,
 				DEF_REG_CONF(CPG_BUS_REG1_MSTOP, GENMASK(3, 0)),
-				RZG2L_PD_F_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON),
 	DEF_PD("wdt0",		R9A08G045_PD_WDT0,
-				DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)), 0),
 	DEF_PD("sdhi0",		R9A08G045_PD_SDHI0,
-				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)), 0),
 	DEF_PD("sdhi1",		R9A08G045_PD_SDHI1,
-				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(1)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(1)), 0),
 	DEF_PD("sdhi2",		R9A08G045_PD_SDHI2,
-				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(11)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(11)), 0),
 	DEF_PD("eth0",		R9A08G045_PD_ETHER0,
-				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(2)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(2)), 0),
 	DEF_PD("eth1",		R9A08G045_PD_ETHER1,
-				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(3)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(3)), 0),
 	DEF_PD("i2c0",		R9A08G045_PD_I2C0,
-				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(10)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(10)), 0),
 	DEF_PD("i2c1",		R9A08G045_PD_I2C1,
-				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(11)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(11)), 0),
 	DEF_PD("i2c2",		R9A08G045_PD_I2C2,
-				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(12)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(12)), 0),
 	DEF_PD("i2c3",		R9A08G045_PD_I2C3,
-				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(13)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(13)), 0),
 	DEF_PD("scif0",		R9A08G045_PD_SCIF0,
-				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(1)),
-				RZG2L_PD_F_NONE),
+				DEF_REG_CONF(CPG_BUS_MCPU2_MSTOP, BIT(1)), 0),
 	DEF_PD("vbat",		R9A08G045_PD_VBAT,
 				DEF_REG_CONF(CPG_BUS_MCPU3_MSTOP, BIT(8)),
-				RZG2L_PD_F_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON),
 };
 
 const struct rzg2l_cpg_info r9a08g045_cpg_info = {
diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index 88bf39e8c79c..b97996e93042 100644
--- a/drivers/clk/renesas/rzg2l-cpg.c
+++ b/drivers/clk/renesas/rzg2l-cpg.c
@@ -1680,11 +1680,13 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
 	return 0;
 }
 
-static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, bool always_on)
+static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, u32 genpd_flags,
+				     bool always_on)
 {
 	struct dev_power_governor *governor;
 
-	pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
+	pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP |
+			   genpd_flags;
 	pd->genpd.attach_dev = rzg2l_cpg_attach_dev;
 	pd->genpd.detach_dev = rzg2l_cpg_detach_dev;
 	if (always_on) {
@@ -1712,7 +1714,7 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
 
 	pd->genpd.name = np->name;
 	pd->priv = priv;
-	ret = rzg2l_cpg_pd_setup(pd, true);
+	ret = rzg2l_cpg_pd_setup(pd, 0, true);
 	if (ret)
 		return ret;
 
@@ -1777,7 +1779,8 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
 		return ret;
 
 	for (unsigned int i = 0; i < info->num_pm_domains; i++) {
-		bool always_on = !!(info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON);
+		u32 genpd_flags = info->pm_domains[i].genpd_flags;
+		bool always_on = !!(genpd_flags & GENPD_FLAG_ALWAYS_ON);
 		struct rzg2l_cpg_pd *pd;
 
 		pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
@@ -1789,7 +1792,7 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
 		pd->id = info->pm_domains[i].id;
 		pd->priv = priv;
 
-		ret = rzg2l_cpg_pd_setup(pd, always_on);
+		ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
 		if (ret)
 			return ret;
 
diff --git a/drivers/clk/renesas/rzg2l-cpg.h b/drivers/clk/renesas/rzg2l-cpg.h
index ecfe7e7ea8a1..881a89b5a710 100644
--- a/drivers/clk/renesas/rzg2l-cpg.h
+++ b/drivers/clk/renesas/rzg2l-cpg.h
@@ -270,14 +270,14 @@ struct rzg2l_cpg_pm_domain_conf {
  * struct rzg2l_cpg_pm_domain_init_data - PM domain init data
  * @name: PM domain name
  * @conf: PM domain configuration
- * @flags: RZG2L PM domain flags (see RZG2L_PD_F_*)
+ * @genpd_flags: genpd flags (see GENPD_FLAG_*)
  * @id: PM domain ID (similar to the ones defined in
  *      include/dt-bindings/clock/<soc-id>-cpg.h)
  */
 struct rzg2l_cpg_pm_domain_init_data {
 	const char * const name;
 	struct rzg2l_cpg_pm_domain_conf conf;
-	u32 flags;
+	u32 genpd_flags;
 	u16 id;
 };
 
@@ -288,13 +288,9 @@ struct rzg2l_cpg_pm_domain_init_data {
 		.conf = { \
 			.mstop = (_mstop_conf), \
 		}, \
-		.flags = (_flags), \
+		.genpd_flags = (_flags), \
 	}
 
-/* Power domain flags. */
-#define RZG2L_PD_F_ALWAYS_ON	BIT(0)
-#define RZG2L_PD_F_NONE		(0)
-
 /**
  * struct rzg2l_cpg_info - SoC-specific CPG Description
  *
-- 
2.39.2

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[Geert Uytterhoeven]

Hi Claudiu,

On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
> to be able to power on the watchdog PM domain from atomic context. For
> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
> for individual PM domains.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/clk/renesas/rzg2l-cpg.c
> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> @@ -1680,11 +1680,13 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
>         return 0;
>  }
>
> -static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, bool always_on)
> +static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, u32 genpd_flags,
> +                                    bool always_on)

You don't need always_on, as that should already be reflected in
genpd_flags.

Also, you could do without passing genpd_flags, if the caller would have
initialized pd->genpd.flags (it already initializes pd->genpd.name).

>  {
>         struct dev_power_governor *governor;
>
> -       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
> +       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP |
> +                          genpd_flags;

Change not needed if the caller would have initialized flags.

>         pd->genpd.attach_dev = rzg2l_cpg_attach_dev;
>         pd->genpd.detach_dev = rzg2l_cpg_detach_dev;
>         if (always_on) {

The next line is

    pd->genpd.flags |= GENPD_FLAG_ALWAYS_ON;

which should already be the case if always_on is true, so it can
be removed.

> @@ -1712,7 +1714,7 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
>
>         pd->genpd.name = np->name;

pd->genpd.flags = GENPD_FLAG_ALWAYS_ON;

>         pd->priv = priv;
> -       ret = rzg2l_cpg_pd_setup(pd, true);
> +       ret = rzg2l_cpg_pd_setup(pd, 0, true);

s/0/GENPD_FLAG_ALWAYS_ON/, FWIW ;-)

>         if (ret)
>                 return ret;
>
> @@ -1777,7 +1779,8 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
>                 return ret;
>
>         for (unsigned int i = 0; i < info->num_pm_domains; i++) {
> -               bool always_on = !!(info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON);
> +               u32 genpd_flags = info->pm_domains[i].genpd_flags;
> +               bool always_on = !!(genpd_flags & GENPD_FLAG_ALWAYS_ON);
>                 struct rzg2l_cpg_pd *pd;
>
>                 pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
> @@ -1789,7 +1792,7 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)

You can add

    pd->genpd.flags = info->pm_domains[i].genpd_flags;

above.

>                 pd->id = info->pm_domains[i].id;
>                 pd->priv = priv;
>
> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
>                 if (ret)
>                         return ret;

What about moving the conditional call to rzg2l_cpg_power_on()
below to rzg2l_cpg_pd_setup()? Then this function no longer needs
the always_on flag.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[claudiu beznea]

Hi, Geert,

On 29.08.2024 15:32, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>
>> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
>> to be able to power on the watchdog PM domain from atomic context. For
>> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
>> for individual PM domains.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
> Thanks for your patch!
> 
>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
>> @@ -1680,11 +1680,13 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
>>         return 0;
>>  }
>>
>> -static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, bool always_on)
>> +static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, u32 genpd_flags,
>> +                                    bool always_on)
> 
> You don't need always_on, as that should already be reflected in
> genpd_flags.

OK.

> 
> Also, you could do without passing genpd_flags, if the caller would have
> initialized pd->genpd.flags (it already initializes pd->genpd.name).

That could be done, indeed.

> 
>>  {
>>         struct dev_power_governor *governor;
>>
>> -       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
>> +       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP |
>> +                          genpd_flags;
> 
> Change not needed if the caller would have initialized flags.

OK

> 
>>         pd->genpd.attach_dev = rzg2l_cpg_attach_dev;
>>         pd->genpd.detach_dev = rzg2l_cpg_detach_dev;
>>         if (always_on) {
> 
> The next line is
> 
>     pd->genpd.flags |= GENPD_FLAG_ALWAYS_ON;
> 
> which should already be the case if always_on is true, so it can
> be removed.

OK

> 
>> @@ -1712,7 +1714,7 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
>>
>>         pd->genpd.name = np->name;
> 
> pd->genpd.flags = GENPD_FLAG_ALWAYS_ON;

Agree.

> 
>>         pd->priv = priv;
>> -       ret = rzg2l_cpg_pd_setup(pd, true);
>> +       ret = rzg2l_cpg_pd_setup(pd, 0, true);
> 
> s/0/GENPD_FLAG_ALWAYS_ON/, FWIW ;-)
> 
>>         if (ret)
>>                 return ret;
>>
>> @@ -1777,7 +1779,8 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
>>                 return ret;
>>
>>         for (unsigned int i = 0; i < info->num_pm_domains; i++) {
>> -               bool always_on = !!(info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON);
>> +               u32 genpd_flags = info->pm_domains[i].genpd_flags;
>> +               bool always_on = !!(genpd_flags & GENPD_FLAG_ALWAYS_ON);
>>                 struct rzg2l_cpg_pd *pd;
>>
>>                 pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
>> @@ -1789,7 +1792,7 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
> 
> You can add
> 
>     pd->genpd.flags = info->pm_domains[i].genpd_flags;
> 
> above.

OK

> 
>>                 pd->id = info->pm_domains[i].id;
>>                 pd->priv = priv;
>>
>> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
>> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
>>                 if (ret)
>>                         return ret;
> 
> What about moving the conditional call to rzg2l_cpg_power_on()
> below to rzg2l_cpg_pd_setup()? Then this function no longer needs
> the always_on flag.

That could be done but I think it will involve an extra power on/power off
cycle for the unused domains.

Thank you for your review,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> 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

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[Geert Uytterhoeven]

Hi Claudiu,

On Fri, Aug 30, 2024 at 9:46 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
> On 29.08.2024 15:32, Geert Uytterhoeven wrote:
> > On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> >> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>
> >> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
> >> to be able to power on the watchdog PM domain from atomic context. For
> >> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
> >> for individual PM domains.
> >>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

> >> --- a/drivers/clk/renesas/rzg2l-cpg.c
> >> +++ b/drivers/clk/renesas/rzg2l-cpg.c

> >
> >>                 pd->id = info->pm_domains[i].id;
> >>                 pd->priv = priv;
> >>
> >> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
> >> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
> >>                 if (ret)
> >>                         return ret;
> >
> > What about moving the conditional call to rzg2l_cpg_power_on()
> > below to rzg2l_cpg_pd_setup()? Then this function no longer needs
> > the always_on flag.
>
> That could be done but I think it will involve an extra power on/power off
> cycle for the unused domains.

Still only to be done for the always-on domain, of course.
Anyway, up to you.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[claudiu beznea]

Hi, Geert,

On 30.08.2024 11:06, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Fri, Aug 30, 2024 at 9:46 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
>> On 29.08.2024 15:32, Geert Uytterhoeven wrote:
>>> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>
>>>> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
>>>> to be able to power on the watchdog PM domain from atomic context. For
>>>> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
>>>> for individual PM domains.
>>>>
>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
>>>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>>>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> 
>>>
>>>>                 pd->id = info->pm_domains[i].id;
>>>>                 pd->priv = priv;
>>>>
>>>> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
>>>> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
>>>>                 if (ret)
>>>>                         return ret;
>>>
>>> What about moving the conditional call to rzg2l_cpg_power_on()
>>> below to rzg2l_cpg_pd_setup()? Then this function no longer needs
>>> the always_on flag.
>>
>> That could be done but I think it will involve an extra power on/power off
>> cycle for the unused domains.
> 
> Still only to be done for the always-on domain, of course.
> Anyway, up to you.

I checked your proposal. If unconditional power on is going to be done for
all the registered domains it may happen to register domains for which
there are no enabled nodes in device tree and thus the domains to remain on
(because the driver enables it under the hood and the genpd core doesn't
know about it).

With unconditional power on and the current DTSes the following domains
remain on after booting with r9a08g045s33-smarc.dtb:
- sdhi2
- i2c2
- i2c3

as the domains are registered and powered (while registered) but the nodes
are not enabled in DT.

Thank you,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[Geert Uytterhoeven]

Hi Claudiu,

On Fri, Aug 30, 2024 at 4:07 PM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
> On 30.08.2024 11:06, Geert Uytterhoeven wrote:
> > On Fri, Aug 30, 2024 at 9:46 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
> >> On 29.08.2024 15:32, Geert Uytterhoeven wrote:
> >>> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> >>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >>>>
> >>>> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
> >>>> to be able to power on the watchdog PM domain from atomic context. For
> >>>> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
> >>>> for individual PM domains.
> >>>>
> >>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >
> >>>> --- a/drivers/clk/renesas/rzg2l-cpg.c
> >>>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> >
> >>>
> >>>>                 pd->id = info->pm_domains[i].id;
> >>>>                 pd->priv = priv;
> >>>>
> >>>> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
> >>>> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
> >>>>                 if (ret)
> >>>>                         return ret;
> >>>
> >>> What about moving the conditional call to rzg2l_cpg_power_on()
> >>> below to rzg2l_cpg_pd_setup()? Then this function no longer needs
> >>> the always_on flag.
> >>
> >> That could be done but I think it will involve an extra power on/power off
> >> cycle for the unused domains.
> >
> > Still only to be done for the always-on domain, of course.
> > Anyway, up to you.
>
> I checked your proposal. If unconditional power on is going to be done for
> all the registered domains it may happen to register domains for which
> there are no enabled nodes in device tree and thus the domains to remain on
> (because the driver enables it under the hood and the genpd core doesn't
> know about it).
>
> With unconditional power on and the current DTSes the following domains
> remain on after booting with r9a08g045s33-smarc.dtb:
> - sdhi2
> - i2c2
> - i2c3
>
> as the domains are registered and powered (while registered) but the nodes
> are not enabled in DT.

To make it clear: I did not suggest doing an unconditional power-on.
I merely suggested moving the conditional power-on from
rzg2l_cpg_add_pm_domains() to rzg2l_cpg_pd_setup().

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

[claudiu beznea]

Hi, Geert,

On 30.08.2024 17:26, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Fri, Aug 30, 2024 at 4:07 PM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
>> On 30.08.2024 11:06, Geert Uytterhoeven wrote:
>>> On Fri, Aug 30, 2024 at 9:46 AM claudiu beznea <claudiu.beznea@tuxon.dev> wrote:
>>>> On 29.08.2024 15:32, Geert Uytterhoeven wrote:
>>>>> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
>>>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>>
>>>>>> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
>>>>>> to be able to power on the watchdog PM domain from atomic context. For
>>>>>> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
>>>>>> for individual PM domains.
>>>>>>
>>>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>
>>>>>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>>>>>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
>>>
>>>>>
>>>>>>                 pd->id = info->pm_domains[i].id;
>>>>>>                 pd->priv = priv;
>>>>>>
>>>>>> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
>>>>>> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
>>>>>>                 if (ret)
>>>>>>                         return ret;
>>>>>
>>>>> What about moving the conditional call to rzg2l_cpg_power_on()
>>>>> below to rzg2l_cpg_pd_setup()? Then this function no longer needs
>>>>> the always_on flag.
>>>>
>>>> That could be done but I think it will involve an extra power on/power off
>>>> cycle for the unused domains.
>>>
>>> Still only to be done for the always-on domain, of course.
>>> Anyway, up to you.
>>
>> I checked your proposal. If unconditional power on is going to be done for
>> all the registered domains it may happen to register domains for which
>> there are no enabled nodes in device tree and thus the domains to remain on
>> (because the driver enables it under the hood and the genpd core doesn't
>> know about it).
>>
>> With unconditional power on and the current DTSes the following domains
>> remain on after booting with r9a08g045s33-smarc.dtb:
>> - sdhi2
>> - i2c2
>> - i2c3
>>
>> as the domains are registered and powered (while registered) but the nodes
>> are not enabled in DT.
> 
> To make it clear: I did not suggest doing an unconditional power-on.
> I merely suggested moving the conditional power-on from
> rzg2l_cpg_add_pm_domains() to rzg2l_cpg_pd_setup().

Ah, I see. That can be done. Sorry for confusion.

Thank you,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

[PATCH v2 2/3] clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as IRQ safe

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

If the watchdog is part of a dedicated power domain (as it may be on
RZ/G3S) the watchdog PM domain need to be powered on in the watchdog
restart handler. Currently, only the clocks are enabled in the watchdog
restart handler. To be able to also power on the PM domain we need to
call pm_runtime_resume_and_get() on the watchdog restart handler, mark
the watchdog device as IRQ safe and register the watchdog PM domain
with GENPD_FLAG_IRQ_SAFE.

Register watchdog PM domain as IRQ safe. Along with it the always-on
PM domain (parent of the watchdog domain) was marked as IRQ safe.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v2:
- changed patch title; it was "clk: renesas: rzg2l-cpg: Mark
  watchdog and always-on PM domains as IRQ safe"

Changes since RFC:
- none; this patch is new

 drivers/clk/renesas/r9a08g045-cpg.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/renesas/r9a08g045-cpg.c b/drivers/clk/renesas/r9a08g045-cpg.c
index ec0672651fe0..8e4f17c21dd7 100644
--- a/drivers/clk/renesas/r9a08g045-cpg.c
+++ b/drivers/clk/renesas/r9a08g045-cpg.c
@@ -259,7 +259,7 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
 	/* Keep always-on domain on the first position for proper domains registration. */
 	DEF_PD("always-on",	R9A08G045_PD_ALWAYS_ON,
 				DEF_REG_CONF(0, 0),
-				GENPD_FLAG_ALWAYS_ON),
+				GENPD_FLAG_ALWAYS_ON | GENPD_FLAG_IRQ_SAFE),
 	DEF_PD("gic",		R9A08G045_PD_GIC,
 				DEF_REG_CONF(CPG_BUS_ACPU_MSTOP, BIT(3)),
 				GENPD_FLAG_ALWAYS_ON),
@@ -270,7 +270,8 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
 				DEF_REG_CONF(CPG_BUS_REG1_MSTOP, GENMASK(3, 0)),
 				GENPD_FLAG_ALWAYS_ON),
 	DEF_PD("wdt0",		R9A08G045_PD_WDT0,
-				DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)), 0),
+				DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)),
+				GENPD_FLAG_IRQ_SAFE),
 	DEF_PD("sdhi0",		R9A08G045_PD_SDHI0,
 				DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)), 0),
 	DEF_PD("sdhi1",		R9A08G045_PD_SDHI1,
-- 
2.39.2

Re: [PATCH v2 2/3] clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as IRQ safe

[Geert Uytterhoeven]

Hi Claudiu,

On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> If the watchdog is part of a dedicated power domain (as it may be on
> RZ/G3S) the watchdog PM domain need to be powered on in the watchdog
> restart handler. Currently, only the clocks are enabled in the watchdog
> restart handler. To be able to also power on the PM domain we need to
> call pm_runtime_resume_and_get() on the watchdog restart handler, mark
> the watchdog device as IRQ safe and register the watchdog PM domain
> with GENPD_FLAG_IRQ_SAFE.
>
> Register watchdog PM domain as IRQ safe. Along with it the always-on
> PM domain (parent of the watchdog domain) was marked as IRQ safe.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>
> Changes in v2:
> - changed patch title; it was "clk: renesas: rzg2l-cpg: Mark
>   watchdog and always-on PM domains as IRQ safe"

Thanks for the update!

> --- a/drivers/clk/renesas/r9a08g045-cpg.c
> +++ b/drivers/clk/renesas/r9a08g045-cpg.c
> @@ -259,7 +259,7 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
>         /* Keep always-on domain on the first position for proper domains registration. */
>         DEF_PD("always-on",     R9A08G045_PD_ALWAYS_ON,
>                                 DEF_REG_CONF(0, 0),
> -                               GENPD_FLAG_ALWAYS_ON),
> +                               GENPD_FLAG_ALWAYS_ON | GENPD_FLAG_IRQ_SAFE),
>         DEF_PD("gic",           R9A08G045_PD_GIC,
>                                 DEF_REG_CONF(CPG_BUS_ACPU_MSTOP, BIT(3)),
>                                 GENPD_FLAG_ALWAYS_ON),
> @@ -270,7 +270,8 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
>                                 DEF_REG_CONF(CPG_BUS_REG1_MSTOP, GENMASK(3, 0)),
>                                 GENPD_FLAG_ALWAYS_ON),
>         DEF_PD("wdt0",          R9A08G045_PD_WDT0,
> -                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)), 0),
> +                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)),
> +                               GENPD_FLAG_IRQ_SAFE),
>         DEF_PD("sdhi0",         R9A08G045_PD_SDHI0,
>                                 DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)), 0),
>         DEF_PD("sdhi1",         R9A08G045_PD_SDHI1,

Can't you just do this for all domains (e.g. in rzg2l_cpg_pd_setup()),
instead of limiting this to the wdt0 and always-on domains?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

RE: [PATCH v2 2/3] clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as IRQ safe

[Biju Das]

Hi Geert,

> -----Original Message-----
> From: Geert Uytterhoeven <geert@linux-m68k.org>
> Sent: Thursday, August 29, 2024 1:45 PM
> Subject: Re: [PATCH v2 2/3] clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as IRQ
> safe
> 
> Hi Claudiu,
> 
> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> >
> > If the watchdog is part of a dedicated power domain (as it may be on
> > RZ/G3S) the watchdog PM domain need to be powered on in the watchdog
> > restart handler. Currently, only the clocks are enabled in the
> > watchdog restart handler. To be able to also power on the PM domain we
> > need to call pm_runtime_resume_and_get() on the watchdog restart
> > handler, mark the watchdog device as IRQ safe and register the
> > watchdog PM domain with GENPD_FLAG_IRQ_SAFE.
> >
> > Register watchdog PM domain as IRQ safe. Along with it the always-on
> > PM domain (parent of the watchdog domain) was marked as IRQ safe.
> >
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> > ---
> >
> > Changes in v2:
> > - changed patch title; it was "clk: renesas: rzg2l-cpg: Mark
> >   watchdog and always-on PM domains as IRQ safe"
> 
> Thanks for the update!
> 
> > --- a/drivers/clk/renesas/r9a08g045-cpg.c
> > +++ b/drivers/clk/renesas/r9a08g045-cpg.c
> > @@ -259,7 +259,7 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
> >         /* Keep always-on domain on the first position for proper domains registration. */
> >         DEF_PD("always-on",     R9A08G045_PD_ALWAYS_ON,
> >                                 DEF_REG_CONF(0, 0),
> > -                               GENPD_FLAG_ALWAYS_ON),
> > +                               GENPD_FLAG_ALWAYS_ON |
> > + GENPD_FLAG_IRQ_SAFE),
> >         DEF_PD("gic",           R9A08G045_PD_GIC,
> >                                 DEF_REG_CONF(CPG_BUS_ACPU_MSTOP, BIT(3)),
> >                                 GENPD_FLAG_ALWAYS_ON), @@ -270,7
> > +270,8 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
> >                                 DEF_REG_CONF(CPG_BUS_REG1_MSTOP, GENMASK(3, 0)),
> >                                 GENPD_FLAG_ALWAYS_ON),
> >         DEF_PD("wdt0",          R9A08G045_PD_WDT0,
> > -                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)), 0),
> > +                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)),
> > +                               GENPD_FLAG_IRQ_SAFE),
> >         DEF_PD("sdhi0",         R9A08G045_PD_SDHI0,
> >                                 DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)), 0),
> >         DEF_PD("sdhi1",         R9A08G045_PD_SDHI1,
> 
> Can't you just do this for all domains (e.g. in rzg2l_cpg_pd_setup()), instead of limiting this to the
> wdt0 and always-on domains?

Not sure, that will make all PM calls for all domains with interrupt disabled??

Cheers,
Biju

Re: [PATCH v2 2/3] clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as IRQ safe

[claudiu beznea]

Hi, Geert,

On 29.08.2024 15:45, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>
>> If the watchdog is part of a dedicated power domain (as it may be on
>> RZ/G3S) the watchdog PM domain need to be powered on in the watchdog
>> restart handler. Currently, only the clocks are enabled in the watchdog
>> restart handler. To be able to also power on the PM domain we need to
>> call pm_runtime_resume_and_get() on the watchdog restart handler, mark
>> the watchdog device as IRQ safe and register the watchdog PM domain
>> with GENPD_FLAG_IRQ_SAFE.
>>
>> Register watchdog PM domain as IRQ safe. Along with it the always-on
>> PM domain (parent of the watchdog domain) was marked as IRQ safe.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>> ---
>>
>> Changes in v2:
>> - changed patch title; it was "clk: renesas: rzg2l-cpg: Mark
>>   watchdog and always-on PM domains as IRQ safe"
> 
> Thanks for the update!
> 
>> --- a/drivers/clk/renesas/r9a08g045-cpg.c
>> +++ b/drivers/clk/renesas/r9a08g045-cpg.c
>> @@ -259,7 +259,7 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
>>         /* Keep always-on domain on the first position for proper domains registration. */
>>         DEF_PD("always-on",     R9A08G045_PD_ALWAYS_ON,
>>                                 DEF_REG_CONF(0, 0),
>> -                               GENPD_FLAG_ALWAYS_ON),
>> +                               GENPD_FLAG_ALWAYS_ON | GENPD_FLAG_IRQ_SAFE),
>>         DEF_PD("gic",           R9A08G045_PD_GIC,
>>                                 DEF_REG_CONF(CPG_BUS_ACPU_MSTOP, BIT(3)),
>>                                 GENPD_FLAG_ALWAYS_ON),
>> @@ -270,7 +270,8 @@ static const struct rzg2l_cpg_pm_domain_init_data r9a08g045_pm_domains[] = {
>>                                 DEF_REG_CONF(CPG_BUS_REG1_MSTOP, GENMASK(3, 0)),
>>                                 GENPD_FLAG_ALWAYS_ON),
>>         DEF_PD("wdt0",          R9A08G045_PD_WDT0,
>> -                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)), 0),
>> +                               DEF_REG_CONF(CPG_BUS_REG0_MSTOP, BIT(0)),
>> +                               GENPD_FLAG_IRQ_SAFE),
>>         DEF_PD("sdhi0",         R9A08G045_PD_SDHI0,
>>                                 DEF_REG_CONF(CPG_BUS_PERI_COM_MSTOP, BIT(0)), 0),
>>         DEF_PD("sdhi1",         R9A08G045_PD_SDHI1,
> 
> Can't you just do this for all domains (e.g. in rzg2l_cpg_pd_setup()),
> instead of limiting this to the wdt0 and always-on domains?

I thought about it but this, too, but I wasn't sure about the behavior of
the currently unexplored drivers for RZ/G3S. AFAICT from the current code
investigation, if this approach is implemented we need to be sure there is
no sleeping in drivers runtime PM APIs.

Thank you,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

[PATCH v2 3/3] watchdog: rzg2l_wdt: Power on the watchdog domain in the restart handler

[Claudiu]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

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 for RZ/G3S with old device trees and
the rest of the SoCs that use 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.

Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v2:
- adjusted patch description and comment from code
- collected tags

Changes since RFC:
- use pm_runtime_resume_and_get() and pm_runtime_irq_safe()
- drop clock prepare in probe

 drivers/watchdog/rzg2l_wdt.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
index 2a35f890a288..11bbe48160ec 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 +167,22 @@ 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 SoCs not registering a watchdog IRQ safe power
+	 * domain 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 +290,7 @@ 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

Re: [PATCH v2 3/3] watchdog: rzg2l_wdt: Power on the watchdog domain in the restart handler

[Ulf Hansson]

On Wed, 28 Aug 2024 at 16:06, Claudiu <claudiu.beznea@tuxon.dev> wrote:
>
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> 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 for RZ/G3S with old device trees and
> the rest of the SoCs that use 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.
>
> Acked-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
>
> Changes in v2:
> - adjusted patch description and comment from code
> - collected tags
>
> Changes since RFC:
> - use pm_runtime_resume_and_get() and pm_runtime_irq_safe()
> - drop clock prepare in probe
>
>  drivers/watchdog/rzg2l_wdt.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> index 2a35f890a288..11bbe48160ec 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 +167,22 @@ 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 SoCs not registering a watchdog IRQ safe power
> +        * domain 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 +290,7 @@ 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
>