On Saturday, July 18, 2015 02:01:40 AM Rafael J. Wysocki wrote:

On Thursday, July 09, 2015 02:04:18 PM Ashwin Chaugule wrote:

quoted

The ACPI processor driver is currently tied too closely
to the ACPI P-states (PSS) and other related constructs
for controlling CPU performance.

The newer ACPI specification (v5.1 onwards) introduces
alternative methods to PSS. These new mechanisms are
described within each ACPI Processor object and so they
need to be scanned whenever a new Processor object is detected.
This patch introduces a new Kconfig symbol to allow for
finer configurability among the two options for controlling
performance states. There is no change in functionality and
the option is auto-selected by the architecture Kconfig files.

The following patchwork introduces CPPC: A newer method of
controlling CPU performance. The OS is not expected to support
CPPC and PSS at runtime. So the kconfig option lets us make
these two mutually exclusive at compile time.

Signed-off-by: Ashwin Chaugule <redacted>
---
 arch/x86/Kconfig                |  1 +
 drivers/acpi/Kconfig            | 19 ++++++---
 drivers/acpi/Makefile           |  6 +--
 drivers/acpi/processor_driver.c | 86 +++++++++++++++++++++++++------------
 drivers/cpufreq/Kconfig         |  2 +-
 drivers/cpufreq/Kconfig.x86     |  2 +
 include/acpi/processor.h        | 94 +++++++++++++++++++++++++++--------------
 7 files changed, 142 insertions(+), 68 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 226d569..93d150d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -143,6 +143,7 @@ config X86
 	select ACPI_LEGACY_TABLES_LOOKUP if ACPI
 	select X86_FEATURE_NAMES if PROC_FS
 	select SRCU
+	select ACPI_CPU_FREQ_PSS if ACPI

Also, does ia64 not use _PSS-based cpufreq?

Thanks,
Rafael