On 08/07/15 02:27, Ashwin Chaugule wrote:
On 7 July 2015 at 21:07, Rafael J. Wysocki rjw@rjwysocki.net wrote:
On Monday, June 15, 2015 04:09:06 PM Ashwin Chaugule wrote:
The ACPI processor driver is currently tied too closely to the ACPI C-states (CST), P-states (PSS) and other related constructs for controlling CPU idle and CPU performance.
The newer ACPI specification (v5.1 onwards) introduces alternative methods to CST and 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 two new Kconfig symbols to allow for finer configurability among the various options for controlling CPU idle and performance states. There is no change in functionality and these options are defaulted to enabled to maintain previous behaviour.
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 ashwin.chaugule@linaro.org Reviewed-by: Al Stone al.stone@linaro.org
drivers/acpi/Kconfig | 31 +++++++++-- drivers/acpi/Makefile | 7 ++- drivers/acpi/processor_driver.c | 86 ++++++++++++++++++---------- drivers/cpufreq/Kconfig | 2 +- drivers/cpufreq/Kconfig.x86 | 2 + include/acpi/processor.h | 120 ++++++++++++++++++++++++++++------------ 6 files changed, 176 insertions(+), 72 deletions(-)
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index ab2cbb5..5942754 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -166,18 +166,39 @@ config ACPI_DOCK This driver supports ACPI-controlled docking stations and removable drive bays such as the IBM Ultrabay and the Dell Module Bay.
-config ACPI_PROCESSOR
tristate "Processor"select THERMALselect CPU_IDLE+config ACPI_CST
bool "ACPI C states (CST) driver"depends on ACPI_PROCESSOR depends on X86 || IA64select CPU_IDLE default y help This driver installs ACPI as the idle handler for Linux and uses ACPI C2 and C3 processor states to save power on systems that
support it. It is required by several flavors of cpufreq
support it.+config ACPI_PSS
bool "ACPI P States (PSS) driver"depends on ACPI_PROCESSORdepends on X86 || IA64select THERMALdefault yhelpThis driver implements ACPI methods for controlling CPU performanceusing PSS methods as described in the ACPI spec. It also enables supportfor ACPI based performance throttling (TSS) and ACPI based thermalmonitoring. It is required by several flavors of cpufreq performance-state drivers.For starters, I don't like these new Kconfig options.
Isn't there a way to implement what you need without adding them?
We need to use the ACPI Processor driver for CPPC without including all its current dependencies. (i.e. PSS, TSS, CSS etc.). The upcoming LPI work from Sudeep will also face the same issue.
Ashwin, I am trying to keep Kconfig options minimum, iff necessary and selected by ARCH code(i.e. not user selectable). Also I am not entirely sure if we need to make PSS and CPPC mutually exclusive.
I had seen patches to support PSS on ARM and if we have to support single Image to handle both they can't be exclusive.
Regards, Sudeep