linux-kernel - Re: [PATCH v4 0/9] Prefer using _OSC method over deprecated

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Message-ID: <3849da12-c8b7-ff0b-77ac-48864009948a@intel.com>
Date:   Mon, 17 Jul 2023 12:49:16 +0200
From:   "Wilczynski, Michal" <michal.wilczynski@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     <linux-acpi@...r.kernel.org>, <andriy.shevchenko@...el.com>,
        <artem.bityutskiy@...ux.intel.com>, <mingo@...hat.com>,
        <bp@...en8.de>, <dave.hansen@...ux.intel.com>, <hpa@...or.com>,
        <lenb@...nel.org>, <jgross@...e.com>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>
Subject: Re: [PATCH v4 0/9] Prefer using _OSC method over deprecated _PDC



On 7/14/2023 6:12 PM, Rafael J. Wysocki wrote:
> On Mon, Jul 10, 2023 at 4:06 PM Michal Wilczynski
> <michal.wilczynski@...el.com> wrote:
>> ACPI 3.0 introduced a new Operating System Capabilities _OSC control
>> method. This method is similar to _PDC, which was marked as deprecated
>> in ACPI 3.0.
>>
>> Prefer using _OSC method over deprecated _PDC in the acpi_bus_init(). In
>> case of the failure of the _OSC, try using _PDC as a fallback.
>>
>> Testing done:
>> Tested on physical server with BIOS implementing _OSC methods. In this
>> case acpi_processor_osc() was executed for each CPU core. acpi_run_osc()
>> returned success indicating that _OSC method succeeded.
>>
>> Tested on qemu VM to check whether the code would work on a SeaBios (the
>> default for qemu, doesn't support _OSC methods, or _PDC). This way I was
>> able to see how code behaves in case BIOS doesn't implement _OSC. In
>> that case the function
>> acpi_run_osc() returned failure, which propagated all the way up to
>> acpi_early_processor_osc(). The logic responsible for triggering _PDC
>> execution was triggered correctly.
>>
>> Tested this using debug messages with printk.
>>
>> v4:
>>  - move setting processor capabilities bits into arch code
>>  - move workaround for mwait to acpi/x86 directory
>>  - rename ACPI_PDC* constants to more generic ACPI_PROC_CAP*
>>  - introduce new function acpi_early_processor_control_setup()
>>
>> v3:
>>  - split into more commits to make review easier
>>  - changed "_UID" to METHOD_NAME_UID
>>  - changed hard-coded constant to ACPI_PDC_COLLAB_PROC_PERF
>>  - added Suggested-by tags
>>  - fixed style issues
>>  - fixed whitespaces
>>  - refactored code
>> v2:
>>  - fixed compilation issues on ia64 and arm
>>
>> Michal Wilczynski (9):
>>   acpi: Move mwait quirk out of acpi_processor.c
>>   acpi: Move processor_physically_present() to acpi_processor.c
>>   acpi: Refactor arch_acpi_set_pdc_bits()
>>   acpi: Rename ACPI_PDC constants
>>   acpi: Clear C_C2C3_FFH and C_C1_FFH in arch_acpi_set_proc_cap_bits()
>>   acpi: Move setting CAP_SMP_T_SWCOORD to arch_acpi_set_proc_cap_bits()
>>   acpi: Introduce acpi_processor_osc()
>>   acpi: Use _OSC method to convey processor OSPM capabilities
>>   acpi: Remove acpi_hwp_native_thermal_lvt_osc()
> I have made a number of changes to the patches (edited subjects,
> rewrote changelogs, fixed up whitespace in a few places, changed the
> return value of acpi_early_processor_osc() to bool and made it static
> etc.) and tentatively queued them up for 6.6.  Please see the
> bleeding-edge branch of linux-pm.git.
>
> I have made sure that the series will still compile at least on
> x86-64, but testing it again would be appreciated.
>
> Thanks!

Thanks, will re-test on linux-pm