Message-ID: <CAPDyKFoiEg4e=p5ikercUQnzTm1FnqE3oj6K=BGo6nEDzrNFig@mail.gmail.com>
Date:   Tue, 19 Jul 2022 11:52:37 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Lucas Stach <l.stach@...gutronix.de>
Cc:     Martin Kepplinger <martin.kepplinger@...i.sm>, rafael@...nel.org,
        khilman@...nel.org, robh@...nel.org,
        krzysztof.kozlowski@...aro.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, festevam@...il.com, pavel@....cz,
        kernel@...i.sm, linux-imx@....com, broonie@...nel.org,
        aford173@...il.com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 1/2] power: domain: handle power supplies that need interrupts

On Tue, 19 Jul 2022 at 11:06, Lucas Stach <l.stach@...gutronix.de> wrote:
>
> 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@...i.sm> 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@pengutronix.de/
> > > 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@puri.sm/T/
> > >
> > > Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
> > > ---
> > >
> > > 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@puri.sm/
> > >
> > > v1: (initial idea)
> > > https://lore.kernel.org/linux-arm-kernel/20220711094549.3445566-1-martin.kepplinger@puri.sm/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.

Alright, thanks for confirming!

>
> 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.

Yes, that sounds like a good idea.

>
> Regards,
> Lucas
>

Kind regards
Uffe

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