Re: [PATCH v1 5/9] ACPI: processor: idle: Add the verification of processor FFH LPI state

[lihuisong (C)]

在 2025/10/23 18:35, Rafael J. Wysocki 写道:
> On Thu, Oct 23, 2025 at 12:17 PM lihuisong (C) <lihuisong@xxxxxxxxxx> wrote:
> > 在 2025/10/22 3:42, Rafael J. Wysocki 写道:
> > > On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@xxxxxxxxxx> wrote:
> > > > Both ARM64 and RISCV architecture would validate Entry Method of LPI
> > > > state and SBI HSM or PSCI cpu suspend. Driver should return failure
> > > > if FFH of LPI state are not ok.
> > > First of all, I cannot parse this changelog, so I don't know the
> > > motivation for the change.
> > Sorry for your confusion.
> > > Second, if _LPI is ever used on x86, the
> > > acpi_processor_ffh_lpi_probe() in acpi_processor_get_power_info() will
> > > get in the way.
> > AFAICS, it's also ok if X86 platform use LPI.
> No, because it returns an error by default as it stands today.
>
> > > Why does the evaluation in acpi_processor_setup_cpuidle_dev() not work?
> > The acpi_processor_ffh_lpi_probe does verify the validity of LPI for ARM
> > and RISCV.
> > But the caller of the acpi_processor_setup_cpuidle_dev()don't verify the
> > return value.
> > In addition, from the name of acpi_processor_setup_cpuidle_dev(), its
> > main purpose is to setup cpudile device rather than to verify LPI.
> That's fair enough.
>
> Also, the list of idle states belongs to the cpuidle driver, not to a
> cpuidle device.
>
> > So I move it to a more prominent position and redefine the
> > acpi_processor_setup_cpuidle_dev to void in patch 9/9.
> > > > Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
> > > > Signed-off-by: Huisong Li <lihuisong@xxxxxxxxxx>
> > > > ---
> > > >    drivers/acpi/processor_idle.c | 10 ++++++++--
> > > >    1 file changed, 8 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > > > index 5684925338b3..b0d6b51ee363 100644
> > > > --- a/drivers/acpi/processor_idle.c
> > > > +++ b/drivers/acpi/processor_idle.c
> > > > @@ -1264,7 +1264,7 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
> > > >
> > > >           dev->cpu = pr->id;
> > > >           if (pr->flags.has_lpi)
> > > > -               return acpi_processor_ffh_lpi_probe(pr->id);
> > > > +               return 0;
> > > >
> > > >           return acpi_processor_setup_cpuidle_cx(pr, dev);
> > > >    }
> > > > @@ -1275,7 +1275,13 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
> > > >
> > > >           ret = acpi_processor_get_lpi_info(pr);
> > > >           if (ret)
> So I think it would be better to check it here, that is
>
> if (!ret) {
>         ret = acpi_processor_ffh_lpi_probe(pr->id));
>         if (!ret)
>                 return 0;
>
>         pr_info("CPU%d: FFH LPI state is invalid\n", pr->id);
>         pr->flags.has_lpi = 0;
> }
>
> return acpi_processor_get_cstate_info(pr);
>
> And the default acpi_processor_ffh_lpi_probe() needs to be changed to return 0.
Sorry, I don't understand why pr->flags.has_lpi is true if 
acpi_processor_ffh_lpi_probe() return failure.
In addition, X86 platform doesn't define acpi_processor_ffh_lpi_probe(). 
this function will return EOPNOTSUPP.
> > > > -               ret = acpi_processor_get_cstate_info(pr);
> > > > +               return acpi_processor_get_cstate_info(pr);
> > > > +
> > > > +       if (pr->flags.has_lpi) {
> > > > +               ret = acpi_processor_ffh_lpi_probe(pr->id);
> > > > +               if (ret)
> > > > +                       pr_err("Processor FFH LPI state is invalid.\n");
> > > > +       }
> > > >
> > > >           return ret;
> > > >    }
> > > > --