On Sun, Mar 12, 2023 at 5:09 PM Zhang, Rui <rui.zhang@xxxxxxxxx> wrote:
>
> On Fri, 2023-03-03 at 20:19 +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > The cpufreq policy notifier in the ACPI processor driver may as
> > well be registered before the driver itself, which causes
> > acpi_processor_cpufreq_init to be true (unless the notifier
> > registration fails, which is unlikely at that point) when the
> > ACPI CPU thermal cooling devices are registered, so the
> > processor_get_max_state() result does not change while
> > acpi_processor_driver_init() is running.
> >
> > Change the ordering in acpi_processor_driver_init() accordingly
> > to prevent the max_state value from remaining 0 permanently for all
> > ACPI CPU cooling devices.
> >
> > Fixes: a365105c685c("thermal: sysfs: Reuse cdev->max_state")
> > Reported-by: Wang, Quanxian <quanxian.wang@xxxxxxxxx>
> > Link:
> > https://lore.kernel.org/linux-pm/53ec1f06f61c984100868926f282647e57ecfb2d.camel@xxxxxxxxx/
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> The full patch series fixes the problem but this one does not.
That is a correct observation, but the $subject patch fixes part of
the problem (which is not addressed by the rest of the series AFAICS)
and so it deserves a Fixes tag of its own IMO.
I guess I should clarify that in the changelog.
> This is because,
>
> static int cpu_has_cpufreq(unsigned int cpu)
> {
> struct
> cpufreq_policy *policy;
>
> if (!acpi_processor_cpufreq_init)
> return 0;
>
> policy = cpufreq_cpu_get(cpu);
> if (policy) {
> cpufreq_cpu_put(policy);
> return 1;
> }
> return 0;
> }
>
> Although acpi_processor_cpufreq_init is set to true with patch 1/4, but
> we don't have cpufreq driver registered, thus cpufreq_cpu_get() return
> NULL.
> so acpi_processor_cpufreq_init is not the only dependency here. :(
Right. That's why the other patches in the series are needed too.
> > ---
> > drivers/acpi/processor_driver.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > Index: linux-pm/drivers/acpi/processor_driver.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/processor_driver.c
> > +++ linux-pm/drivers/acpi/processor_driver.c
> > @@ -263,6 +263,12 @@ static int __init acpi_processor_driver_
> > if (acpi_disabled)
> > return 0;
> >
> > + if (!cpufreq_register_notifier(&acpi_processor_notifier_block,
> > + CPUFREQ_POLICY_NOTIFIER)) {
> > + acpi_processor_cpufreq_init = true;
> > + acpi_processor_ignore_ppc_init();
> > + }
> > +
> > result = driver_register(&acpi_processor_driver);
> > if (result < 0)
> > return result;
> > @@ -276,12 +282,6 @@ static int __init acpi_processor_driver_
> > cpuhp_setup_state_nocalls(CPUHP_ACPI_CPUDRV_DEAD, "acpi/cpu-
> > drv:dead",
> > NULL, acpi_soft_cpu_dead);
> >
> > - if (!cpufreq_register_notifier(&acpi_processor_notifier_block,
> > - CPUFREQ_POLICY_NOTIFIER)) {
> > - acpi_processor_cpufreq_init = true;
> > - acpi_processor_ignore_ppc_init();
> > - }
> > -
> > acpi_processor_throttling_init();
> > return 0;
> > err:
> >
> >
> >
