linux-kernel - [PATCH v3 0/5] Prefer using _OSC method over deprecated

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Date:   Tue, 13 Jun 2023 19:10:29 +0300
From:   Michal Wilczynski <michal.wilczynski@...el.com>
To:     linux-acpi@...r.kernel.org
Cc:     rafael@...nel.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: [PATCH v3 0/5] Prefer using _OSC method over deprecated _PDC

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.

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 (5):
  acpi: Move logic responsible for conveying processor OSPM capabilities
  acpi: Refactor arch_acpi_set_pdc_bits()
  acpi: Introduce new function callback for _OSC
  acpi: Use _OSC method to convey processor OSPM capabilities
  acpi: Remove acpi_hwp_native_thermal_lvt_osc()

 arch/ia64/include/asm/acpi.h  |   4 +-
 arch/x86/include/asm/acpi.h   |  13 +--
 drivers/acpi/acpi_processor.c | 151 +++++++++++++++++++++++++++-------
 drivers/acpi/bus.c            |  13 ++-
 drivers/acpi/internal.h       |  10 +--
 drivers/acpi/processor_pdc.c  |  82 +-----------------
 include/acpi/pdc_intel.h      |   1 +
 include/acpi/processor.h      |   2 +-
 8 files changed, 148 insertions(+), 128 deletions(-)

-- 
2.41.0