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    SubjectRe: [PATCH v6 1/2] power: domain: handle genpd correctly when needing interrupts
    On Thu, 25 Aug 2022 at 09:06, Martin Kepplinger
    <martin.kepplinger@puri.sm> wrote:
    >
    > Am Mittwoch, dem 24.08.2022 um 15:30 +0200 schrieb Ulf Hansson:
    > > On Mon, 22 Aug 2022 at 10:38, Martin Kepplinger
    > > <martin.kepplinger@puri.sm> wrote:
    > > >
    > > > Am Freitag, dem 19.08.2022 um 16:53 +0200 schrieb Ulf Hansson:
    > > > > On Fri, 19 Aug 2022 at 11:17, Martin Kepplinger
    > > > > <martin.kepplinger@puri.sm> wrote:
    > > > > >
    > > > > > Am Dienstag, dem 26.07.2022 um 17:07 +0200 schrieb Ulf Hansson:
    > > > > > > On Tue, 26 Jul 2022 at 10:33, Martin Kepplinger
    > > > > > > <martin.kepplinger@puri.sm> wrote:
    > > > > > > >
    > > > > > > > If for example 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
    > > > > > > > many other
    > > > > > > > boards too.
    > > > > > > >
    > > > > > > > This is designed so that genpd providers just say "this
    > > > > > > > genpd
    > > > > > > > needs
    > > > > > > > interrupts" (by setting the flag) - without implying an
    > > > > > > > implementation.
    > > > > > > >
    > > > > > > > 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@puri.sm>
    > > > > > > > ---
    > > > > > > > drivers/base/power/domain.c | 13 +++++++++++--
    > > > > > > > include/linux/pm_domain.h | 5 +++++
    > > > > > > > 2 files changed, 16 insertions(+), 2 deletions(-)
    > > > > > > >
    > > > > > > > diff --git a/drivers/base/power/domain.c
    > > > > > > > b/drivers/base/power/domain.c
    > > > > > > > index 5a2e0232862e..58376752a4de 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_irq_on(genpd) (genpd->flags &
    > > > > > > > GENPD_FLAG_IRQ_ON)
    > > > > > > >
    > > > > > > > static inline bool irq_safe_dev_in_sleep_domain(struct
    > > > > > > > device
    > > > > > > > *dev,
    > > > > > > > const struct generic_pm_domain *genpd)
    > > > > > > > @@ -2065,8 +2066,15 @@ int pm_genpd_init(struct
    > > > > > > > generic_pm_domain
    > > > > > > > *genpd,
    > > > > > > > genpd->domain.ops.runtime_suspend =
    > > > > > > > genpd_runtime_suspend;
    > > > > > > > genpd->domain.ops.runtime_resume =
    > > > > > > > genpd_runtime_resume;
    > > > > > > > genpd->domain.ops.prepare = genpd_prepare;
    > > > > > > > - genpd->domain.ops.suspend_noirq =
    > > > > > > > genpd_suspend_noirq;
    > > > > > > > - genpd->domain.ops.resume_noirq =
    > > > > > > > genpd_resume_noirq;
    > > > > > > > +
    > > > > > > > + if (genpd_irq_on(genpd)) {
    > > > > > > > + genpd->domain.ops.suspend =
    > > > > > > > genpd_suspend_noirq;
    > > > > > > > + genpd->domain.ops.resume =
    > > > > > > > genpd_resume_noirq;
    > > > > > > > + } else {
    > > > > > > > + genpd->domain.ops.suspend_noirq =
    > > > > > > > genpd_suspend_noirq;
    > > > > > > > + genpd->domain.ops.resume_noirq =
    > > > > > > > genpd_resume_noirq;
    > > > > > >
    > > > > > > As we discussed previously, I am thinking that it may be
    > > > > > > better
    > > > > > > to
    > > > > > > move to using genpd->domain.ops.suspend_late and
    > > > > > > genpd->domain.ops.resume_early instead.
    > > > > >
    > > > > > Wouldn't that better be a separate patch (on top)? Do you
    > > > > > really
    > > > > > want
    > > > > > me to change the current behaviour (default case) to from noirq
    > > > > > to
    > > > > > late? Then I'll resend this series with such a patch added.
    > > > >
    > > > > Sorry, I wasn't clear enough, the default behaviour should remain
    > > > > as
    > > > > is.
    > > > >
    > > > > What I meant was, when genpd_irq_on() is true, we should use the
    > > > > genpd->domain.ops.suspend_late and genpd-
    > > > > >domain.ops.resume_early.
    > > >
    > > > Testing that shows that this isn't working. I can provide the logs
    > > > later, but suspend fails and I think it makes sense: "suspend_late"
    > > > is
    > > > simply already too late when i2c (or any needed driver) uses
    > > > "suspend".
    > >
    > > Okay, I see.
    > >
    > > The reason why I suggested moving the callbacks to "suspend_late",
    > > was
    > > that I was worried that some of the attached devices to genpd could
    > > use "suspend_late" themselves. This is the case for some drivers for
    > > DMA/clock/gpio/pinctrl-controllers, for example. That said, I am
    > > curious to look at the DT files for the platform you are running,
    > > would you mind giving me a pointer?
    >
    > I'm running
    > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
    > with these (small) patches on top:
    > https://source.puri.sm/martin.kepplinger/linux-next/-/commits/5.19.3/librem5

    Thanks for sharing the information!

    >
    > >
    > > So, this made me think about this a bit more. In the end, just using
    > > different levels (suspend, suspend_late, suspend_noirq) of callbacks
    > > are just papering over the real *dependency* problem.
    >
    > true, it doesn't feel like a stable solution.
    >
    > >
    > > What we need for the genpd provider driver, is to be asked to be
    > > suspended under the following conditions:
    > > 1. All consumer devices (and child-domains) for its corresponding PM
    > > domain have been suspended.
    > > 2. All its supplier devices supplies must remain resumed, until the
    > > genpd provider has been suspended.
    > >
    > > Please allow me a few more days to think in more detail about this.
    >
    > Thanks a lot for thinking about this!

    I have made some more thinking, but it's been a busy period for me, so
    unfortunately I need some additional time (another week). It seems
    like I also need to do some prototyping, to convince myself about the
    approach.

    So, my apologies for the delay!

    Kind regards
    Uffe

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