Re: [PATCH 1/1] hw/i386/acpi-build: add OSHP method support for SHPC driver load

["Gao,Shiyuan" via <qemu-devel@nongnu.org>]

> > SHPC driver will be loaded fail in i440fx platform, the dmesg shows
> > that OS cannot get control of SHPC hotplug and hotplug device to
> > the PCI bridge will fail when we use SHPC Native type:
> >
> >   [3.336059] shpchp 0000:00:03.0: Requesting control of SHPC hotplug via OSHP (\_SB_.PCI0.S28_)
> >   [3.337408] shpchp 0000:00:03.0: Requesting control of SHPC hotplug via OSHP (\_SB_.PCI0)
> >   [3.338710] shpchp 0000:00:03.0: Cannot get control of SHPC hotplug
> >
> > Add OSHP method support for SHPC driver load, the hotplug device to the PCI bridge will
> > success when we use SHPC Native type.
> >
> >   [1.703975] shpchp 0000:00:03.0: Requesting control of SHPC hotplug via OSHP (\_SB_.PCI0.S18_)
> >   [1.704934] shpchp 0000:00:03.0: Requesting control of SHPC hotplug via OSHP (\_SB_.PCI0)
> >   [1.705855] shpchp 0000:00:03.0: Gained control of SHPC hotplug (\_SB_.PCI0)
> >   [1.707054] shpchp 0000:00:03.0: HPC vendor_id 1b36 device_id 1 ss_vid 0 ss_did 0
> >
> > According to the acpi_pcihp, the OSHP method don't need parameter and return value now.
> >
> >   shpc_probe
> >     --> acpi_get_hp_hw_control_from_firmware
> >       --> acpi_run_oshp
> >         --> status = acpi_evaluate_object(handle, METHOD_NAME_OSHP, NULL, NULL);
> >
> > Signed-off-by: Shiyuan Gao <gaoshiyuan@baidu.com>
> > ---
> >  hw/i386/acpi-build.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index f4e366f64f..79622e6939 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -1412,6 +1412,18 @@ static void build_acpi0017(Aml *table)
> >      aml_append(table, scope);
> >  }
> >
> > +static Aml *build_oshp_method(void)
> > +{
> > +    Aml *method;
> > +
> > +    /*
> > +     * Request control of SHPC hotplug via OSHP method,
> > +     * no need parameter and return value in acpi_pcihp.
> > +     */
>
> Quote spec and earliest version documenting this, please.

I cann't find document describe this, only find in the kernel code
and describe it in the commit message.