Hi Rafael, On 8 July 2015 at 09:34, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: > Hi Ashwin, > > On Wed, Jul 8, 2015 at 3:27 AM, Ashwin Chaugule > <ashwin.chaugule@xxxxxxxxxx> wrote: >> On 7 July 2015 at 21:07, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> 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@xxxxxxxxxx> >>>> Reviewed-by: Al Stone <al.stone@xxxxxxxxxx> >>>> --- >>>> 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 THERMAL >>>> - select CPU_IDLE >>>> +config ACPI_CST >>>> + bool "ACPI C states (CST) driver" >>>> + depends on ACPI_PROCESSOR >>>> depends on X86 || IA64 >>>> + select 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_PROCESSOR >>>> + depends on X86 || IA64 >>>> + select THERMAL >>>> + default y >>>> + help >>>> + This driver implements ACPI methods for controlling CPU performance >>>> + using PSS methods as described in the ACPI spec. It also enables support >>>> + for ACPI based performance throttling (TSS) and ACPI based thermal >>>> + monitoring. 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. I considered the >> alternative of adding a probe routine which matches >> ACPI_PROCESSOR_OBJECT/DEVICE_HID to each driver, but this seemed like >> a better option. Do you have any other ideas? > > First of all, I don't see what _CST has to do with CPPC. > > Second, it looks like the problem is that x86 probably won't use CPPC, > while arm64 probably won't use _PSS. > > That can be addressed by adding Kconfig options, but those options > should not be user-selectable (because quite honestly users don't have > to know what those things are and they don't care *and* things break > if they make a wrong choice). Instead, I'd make architecture Kconfigs > select those options automatically. > I've made changes locally. Basically s/ACPI_PSS/HAVE_ACPI_PSS/ and in arch/x86/Kconfig; select HAVE_ACPI_PSS if ACPI. Similarly for CST. Just wanted to check if there were any other comments before sending out v7. Thanks, Ashwin. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
