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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Thu, 29 Jun 2023 15:15:53 +0200
Message-ID: <CAJZ5v0gWuU1JPbzYpDZ6YQ4YNydyELQ9tXKcJgmLwe_=fZ521A@mail.gmail.com>
Subject: Re: [PATCH v3 3/5] acpi: Introduce new function callback for _OSC
To:     Michal Wilczynski <michal.wilczynski@intel.com>
Cc:     linux-acpi@vger.kernel.org, rafael@kernel.org,
        andriy.shevchenko@intel.com, artem.bityutskiy@linux.intel.com,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, lenb@kernel.org, jgross@suse.com,
        linux-kernel@vger.kernel.org, x86@kernel.org
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On Thu, Jun 29, 2023 at 1:04 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> I would just say "Introduce acpi_processor_osc()" in the subject and
> then explain its role in the changelog.
>
> On Tue, Jun 13, 2023 at 6:12 PM Michal Wilczynski
> <michal.wilczynski@intel.com> wrote:
> >
> > Currently in ACPI code _OSC method is already used for workaround
> > introduced in commit a21211672c9a ("ACPI / processor: Request native
> > thermal interrupt handling via _OSC"). Create new function, similar to
> > already existing acpi_hwp_native_thermal_lvt_osc(). Call new function
> > acpi_processor_osc(). Make this function fulfill the purpose previously
> > fulfilled by the workaround plus convey OSPM processor capabilities
> > with it by setting correct processor capability bits.
> >
> > Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> >  arch/x86/include/asm/acpi.h   |  3 +++
> >  drivers/acpi/acpi_processor.c | 43 ++++++++++++++++++++++++++++++++++-
> >  include/acpi/pdc_intel.h      |  1 +
> >  3 files changed, 46 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
> > index 6a498d1781e7..6c25ce2dad18 100644
> > --- a/arch/x86/include/asm/acpi.h
> > +++ b/arch/x86/include/asm/acpi.h
> > @@ -112,6 +112,9 @@ static inline void arch_acpi_set_proc_cap_bits(u32 *cap)
> >         if (cpu_has(c, X86_FEATURE_ACPI))
> >                 *cap |= ACPI_PDC_T_FFH;
> >
> > +       if (cpu_has(c, X86_FEATURE_HWP))
> > +               *cap |= ACPI_PDC_COLLAB_PROC_PERF;
> > +
> >         /*
> >          * If mwait/monitor is unsupported, C2/C3_FFH will be disabled
> >          */
> > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> > index 8c5d0295a042..0de0b05b6f53 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -591,13 +591,54 @@ void __init processor_dmi_check(void)
> >         dmi_check_system(processor_idle_dmi_table);
> >  }
> >
> > +/* vendor specific UUID indicating an Intel platform */
> > +static u8 sb_uuid_str[] = "4077A616-290C-47BE-9EBD-D87058713953";
> >  static bool acpi_hwp_native_thermal_lvt_set;
> > +static acpi_status __init acpi_processor_osc(acpi_handle handle, u32 lvl,
> > +                                            void *context, void **rv)
> > +{
> > +       u32 capbuf[2] = {};
> > +       acpi_status status;
> > +       struct acpi_osc_context osc_context = {
> > +               .uuid_str = sb_uuid_str,
> > +               .rev = 1,
> > +               .cap.length = 8,
> > +               .cap.pointer = capbuf,
> > +       };
> > +
> > +       if (processor_physically_present(handle) == false)
>
> if (!processor_physically_present(handle))
>
> > +               return AE_OK;
> > +
> > +       arch_acpi_set_proc_cap_bits(&capbuf[OSC_SUPPORT_DWORD]);
> > +
> > +       if (boot_option_idle_override == IDLE_NOMWAIT)
> > +               capbuf[OSC_SUPPORT_DWORD] &=
> > +                       ~(ACPI_PDC_C_C2C3_FFH | ACPI_PDC_C_C1_FFH);
> > +
> > +       status = acpi_run_osc(handle, &osc_context);
> > +       if (ACPI_FAILURE(status))
> > +               return status;
> > +
> > +       if (osc_context.ret.pointer && osc_context.ret.length > 1) {
> > +               u32 *capbuf_ret = osc_context.ret.pointer;
> > +
> > +               if (!acpi_hwp_native_thermal_lvt_set &&
> > +                   capbuf_ret[1] & ACPI_PDC_COLLAB_PROC_PERF) {
>
> Checking it in capbuf_ret[] if it was not set in capbuf[] is sort of
> questionable.
>
> Note that acpi_hwp_native_thermal_lvt_osc() sets it in capbuf[] before
> calling acpi_run_osc().

So you moved setting it to arch_acpi_set_proc_cap_bits(), but then it
should also be checked by the arch code.  That is, add an arch
function to check if a given bit is set in the returned capabilities
buffer (passed as an argument).

Also it can be argued that ACPI_PDC_C_C2C3_FFH and ACPI_PDC_C_C1_FFH
should be set by the arch code too.

>
> > +                       acpi_handle_info(handle,
> > +                                        "_OSC native thermal LVT Acked\n");
> > +                       acpi_hwp_native_thermal_lvt_set = true;
> > +               }
> > +       }
> > +       kfree(osc_context.ret.pointer);
> > +
> > +       return AE_OK;
> > +}
> > +
> >  static acpi_status __init acpi_hwp_native_thermal_lvt_osc(acpi_handle handle,
> >                                                           u32 lvl,
> >                                                           void *context,
> >                                                           void **rv)
> >  {
> > -       u8 sb_uuid_str[] = "4077A616-290C-47BE-9EBD-D87058713953";
> >         u32 capbuf[2];
> >         struct acpi_osc_context osc_context = {
> >                 .uuid_str = sb_uuid_str,
> > diff --git a/include/acpi/pdc_intel.h b/include/acpi/pdc_intel.h
> > index 967c552d1cd3..9427f639287f 100644
> > --- a/include/acpi/pdc_intel.h
> > +++ b/include/acpi/pdc_intel.h
> > @@ -16,6 +16,7 @@
> >  #define ACPI_PDC_C_C1_FFH              (0x0100)
> >  #define ACPI_PDC_C_C2C3_FFH            (0x0200)
> >  #define ACPI_PDC_SMP_P_HWCOORD         (0x0800)
> > +#define ACPI_PDC_COLLAB_PROC_PERF      (0x1000)
>
> I would call this ACPI_OSC_COLLAB_PROC_PERF to avoid confusion.
>
> It may also be a good idea to introduce ACPI_OSC_ symbols to replace
> the existing ACPI_PDC_ ones (with the same values, respectively) and
> get rid of the latter later.
>
> >  #define ACPI_PDC_EST_CAPABILITY_SMP    (ACPI_PDC_SMP_C1PT | \
> >                                          ACPI_PDC_C_C1_HALT | \
> > --