On 8 July 2015 at 16:05, Ashwin Chaugule ashwin.chaugule@linaro.org wrote:
On 8 July 2015 at 15:55, Rafael J. Wysocki rafael@kernel.org wrote:
Hi Ashwin,
On Wed, Jul 8, 2015 at 9:16 PM, Ashwin Chaugule ashwin.chaugule@linaro.org wrote:
Hi Rafael,
On 8 July 2015 at 09:34, Rafael J. Wysocki rafael@kernel.org wrote:
Hi Ashwin,
On Wed, Jul 8, 2015 at 3:27 AM, Ashwin Chaugule ashwin.chaugule@linaro.org 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 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.
Can you please just send the new version of the $subject patch alone for now?
Attached below. (hope that worked.)
Also I'm still unsure what the connection between _CST and CPPC is.
There isnt. But I'm missing where I've implied the dependency?
Perhaps the confusion is coming from the introduction of ACPI_CST in this file. I could leave it as it is and just separate out the ACPI_PSS bits. But I figured, while I'm at it, I'd introduce ACPI_CST, since we know the LPI stuff is coming up soon as a CST alternative anyway. So if you prefer, I can drop the CST bits and maybe Sudeep can address that as part of his LPI patchset?
Thanks, Ashwin.