On Fri, 12 Apr 2024 20:10:54 +0200
"Rafael J. Wysocki" <rafael@xxxxxxxxxx> wrote:
> On Fri, Apr 12, 2024 at 4:38 PM Jonathan Cameron
> <Jonathan.Cameron@xxxxxxxxxx> wrote:
> >
> > The arm64 specific arch_register_cpu() needs to access the _STA
> > method of the DSDT object so make it available by assigning the
> > appropriate handle to the struct cpu instance.
> >
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > ---
> > drivers/acpi/acpi_processor.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> > index 7a0dd35d62c9..93e029403d05 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -235,6 +235,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
> > union acpi_object object = { 0 };
> > struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
> > struct acpi_processor *pr = acpi_driver_data(device);
> > + struct cpu *c;
> > int device_declaration = 0;
> > acpi_status status = AE_OK;
> > static int cpu0_initialized;
> > @@ -314,6 +315,8 @@ static int acpi_processor_get_info(struct acpi_device *device)
> > cpufreq_add_device("acpi-cpufreq");
> > }
> >
> > + c = &per_cpu(cpu_devices, pr->id);
> > + ACPI_COMPANION_SET(&c->dev, device);
>
> This is also set for per_cpu(cpu_sys_devices, pr->id) in
> acpi_processor_add(), via acpi_bind_one().
Hi Rafael,
cpu_sys_devices gets filled with a pointer to this same structure.
The contents gets set in register_cpu() so at this point
it doesn't point anywhere. As a side note register_cpu()
memsets to zero the value I set it to in the code above which isn't
great, particularly as I want to use this in post_eject for
arm64.
We could make a copy of the handle and put it back after
the memset in register_cpu() but that is also ugly.
It's the best I've come up with to make sure this is still set
come remove time but is rather odd.
>
> Moreover, there is some pr->id validation in acpi_processor_add(), so
> it seems premature to use it here this way.
>
> I think that ACPI_COMPANION_SET() should be called from here on
> per_cpu(cpu_sys_devices, pr->id) after validating pr->id (so the
> pr->id validation should all be done here) and then NULL can be passed
> as acpi_dev to acpi_bind_one() in acpi_processor_add(). Then, there
> will be one physical device corresponding to the processor ACPI device
> and no confusion.
I'm fairly sure this is pointing to the same device but agreed this
is a tiny bit confusing. However we can't use cpu_sys_devices at this point
so I'm not immediately seeing a cleaner solution :(
Jonathan
>
> > /*
> > * Extra Processor objects may be enumerated on MP systems with
> > * less than the max # of CPUs. They should be ignored _iff
> > --
> > 2.39.2
> >
