Re: [PATCH v3 1/2] power: domain: handle power supplies that need interrupts

From: Lucas Stach
Date: Tue Jul 19 2022 - 05:06:29 EST

Am Dienstag, dem 19.07.2022 um 10:53 +0200 schrieb Ulf Hansson:
> On Mon, 18 Jul 2022 at 23:04, Martin Kepplinger
> <martin.kepplinger@xxxxxxx> wrote:
> >
> > If the power-domains' power-supply node (regulator) needs
> > interrupts to work, the current setup with noirq callbacks cannot
> > work; for example a pmic regulator on i2c, when suspending, usually already
> > times out during suspend_noirq:
> >
> > [ 41.024193] buck4: failed to disable: -ETIMEDOUT
> >
> > So fix system suspend and resume for these power-domains by using the
> > "outer" suspend/resume callbacks instead. Tested on the imx8mq-librem5 board,
> > but by looking at the dts, this will fix imx8mq-evk and possibly other boards
> > too.
> >
> > Possibly one can find more changes than suspend/resume for this case. They
> > can be added later when testing them: This is designed so that genpd
> > providers just say "this power-supply" needs interrupts - without implying
> > what exactly should be configured in genpd.
> >
> > Initially system suspend problems had been discussed at
> > https://lore.kernel.org/linux-arm-kernel/20211002005954.1367653-8-l.stach@xxxxxxxxxxxxxx/
> > which led to discussing the pmic that contains the regulators which
> > serve as power-domain power-supplies:
> > https://lore.kernel.org/linux-pm/573166b75e524517782471c2b7f96e03fd93d175.camel@xxxxxxx/T/
> >
> > Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxx>
> > ---
> >
> > revision history
> > ----------------
> > v3: (thank you Ulf)
> > * move DT parsing to gpcv2 and create a genpd flag that gets set
> >
> > v2: (thank you Krzysztof)
> > * rewrite: find possible regulators' interrupts property in parents
> > instead of inventing a new property.
> > https://lore.kernel.org/linux-arm-kernel/20220712121832.3659769-1-martin.kepplinger@xxxxxxx/
> >
> > v1: (initial idea)
> > https://lore.kernel.org/linux-arm-kernel/20220711094549.3445566-1-martin.kepplinger@xxxxxxx/T/#t
> >
> >
> > drivers/base/power/domain.c | 19 +++++++++++++++++++
> > drivers/soc/imx/gpcv2.c | 9 +++++++++
> > include/linux/pm_domain.h | 6 ++++++
> > 3 files changed, 34 insertions(+)
> >
> > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> > index 739e52cd4aba..1437476c9086 100644
> > --- a/drivers/base/power/domain.c
> > +++ b/drivers/base/power/domain.c
> > @@ -130,6 +130,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
> > #define genpd_is_active_wakeup(genpd) (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
> > #define genpd_is_cpu_domain(genpd) (genpd->flags & GENPD_FLAG_CPU_DOMAIN)
> > #define genpd_is_rpm_always_on(genpd) (genpd->flags & GENPD_FLAG_RPM_ALWAYS_ON)
> > +#define genpd_ps_needs_irq(genpd) (genpd->flags & GENPD_FLAG_IRQ_POWER_SUPPLY)
> >
> > static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
> > const struct generic_pm_domain *genpd)
> > @@ -2298,6 +2299,20 @@ static bool genpd_present(const struct generic_pm_domain *genpd)
> > return ret;
> > }
> >
> > +/**
> > + * of_genpd_get_power_supply_irq() - Adjust if power-supply needs interrupts
> > + * @genpd: Pointer to PM domain associated with the PM domain provider.
> > + */
> > +static void of_genpd_config_power_supply_irq(struct generic_pm_domain *pd)
>
> This isn't an "of" function. Moreover, I think we just skip the
> function all together and have the code in pm_genpd_init() instead.
>
> > +{
> > + if (genpd_ps_needs_irq(pd)) {
> > + pd->domain.ops.suspend = genpd_suspend_noirq;
> > + pd->domain.ops.resume = genpd_resume_noirq;
> > + pd->domain.ops.suspend_noirq = NULL;
> > + pd->domain.ops.resume_noirq = NULL;
> > + }
> > +}
> > +
> > /**
> > * of_genpd_add_provider_simple() - Register a simple PM domain provider
> > * @np: Device node pointer associated with the PM domain provider.
> > @@ -2343,6 +2358,8 @@ int of_genpd_add_provider_simple(struct device_node *np,
> > genpd->provider = &np->fwnode;
> > genpd->has_provider = true;
> >
> > + of_genpd_config_power_supply_irq(genpd);
>
> Drop this. As stated above, I think the code belongs in pm_genpd_init().
>
> > +
> > return 0;
> > }
> > EXPORT_SYMBOL_GPL(of_genpd_add_provider_simple);
> > @@ -2394,6 +2411,8 @@ int of_genpd_add_provider_onecell(struct device_node *np,
> >
> > genpd->provider = &np->fwnode;
> > genpd->has_provider = true;
> > +
> > + of_genpd_config_power_supply_irq(genpd);
>
> Ditto.
>
> > }
> >
> > ret = genpd_add_provider(np, data->xlate, data);
> > diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> > index 85aa86e1338a..3a22bad07534 100644
> > --- a/drivers/soc/imx/gpcv2.c
> > +++ b/drivers/soc/imx/gpcv2.c
> > @@ -1303,6 +1303,7 @@ static const struct imx_pgc_domain_data imx8mn_pgc_domain_data = {
> > static int imx_pgc_domain_probe(struct platform_device *pdev)
> > {
> > struct imx_pgc_domain *domain = pdev->dev.platform_data;
> > + struct device_node *dn;
> > int ret;
> >
> > domain->dev = &pdev->dev;
> > @@ -1333,6 +1334,14 @@ static int imx_pgc_domain_probe(struct platform_device *pdev)
> > regmap_update_bits(domain->regmap, domain->regs->map,
> > domain->bits.map, domain->bits.map);
> >
> > + dn = of_parse_phandle(domain->dev->of_node, "power-supply", 0);
> > + if (dn) {
> > + while ((dn = of_get_next_parent(dn))) {
> > + if (of_get_property(dn, "interrupts", NULL))
> > + domain->genpd.flags |= GENPD_FLAG_IRQ_POWER_SUPPLY;
> > + }
> > + }
> > +
> > ret = pm_genpd_init(&domain->genpd, NULL, true);
> > if (ret) {
> > dev_err(domain->dev, "Failed to init power domain\n");
> > diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> > index ebc351698090..bcceaf376f36 100644
> > --- a/include/linux/pm_domain.h
> > +++ b/include/linux/pm_domain.h
> > @@ -60,6 +60,11 @@
> > * GENPD_FLAG_MIN_RESIDENCY: Enable the genpd governor to consider its
> > * components' next wakeup when determining the
> > * optimal idle state.
> > + *
> > + * GENPD_FLAG_IRQ_POWER_SUPPLY: The power-domains' power-supply (regulator)
> > + * needs interrupts to work. Adjust accordingly.
> > + * Use the outer suspend/resume callbacks instead
> > + * of noirq for example.
>
> I prefer a more generic name. How about GENPD_FLAG_IRQ_ON.
>
> For the description, I would rather state that the genpd needs irqs to
> stay on to be able to manage power on/off. Or something along those
> lines.
>
> > */
> > #define GENPD_FLAG_PM_CLK (1U << 0)
> > #define GENPD_FLAG_IRQ_SAFE (1U << 1)
> > @@ -68,6 +73,7 @@
> > #define GENPD_FLAG_CPU_DOMAIN (1U << 4)
> > #define GENPD_FLAG_RPM_ALWAYS_ON (1U << 5)
> > #define GENPD_FLAG_MIN_RESIDENCY (1U << 6)
> > +#define GENPD_FLAG_IRQ_POWER_SUPPLY (1U << 7)
> >
> > enum gpd_status {
> > GENPD_STATE_ON = 0, /* PM domain is on */
> > --
> > 2.30.2
> >
>
> BTW, a more generic question. If you move away from using the *noirq
> callbacks to the other suspend/resume callbacks in genpd to solve this
> problem, that requires all devices that is attached to the PM domain
> (genpd) to also *not* be managed with the "late/early" or the "noirq"
> callbacks too. In other case, we may power off the PM domain while
> some devices may still rely on it to be on.
>
> Are you sure that this is the case?

For the i.MX8M* it should be fine. While we have some devices that are
using the noirq supend/resume callbacks, like PCIe, those are not in a
power-domain where we would like to control an external regulator, so
things should work fine for the targeted use-case.

However, it may be a good idea to introduce some kind of kernel warning
when a driver with noirq suspend/resume callbacks is attached to a
GENPD_FLAG_IRQ_ON domain.

Regards,
Lucas