On 01/12/2012 04:36 AM, Benjamin Herrenschmidt wrote:
> On Wed, 2012-01-11 at 20:37 -0200, Thadeu Lima de Souza Cascardo wrote:
>> On Tue, Jan 10, 2012 at 03:05:35PM -0000, Benjamin Herrenschmidt wrote:
>>> We just replaced the pseries platform idle loops with a cpuidle backend,
>>> however that means that you won't get any power saving and won't return
>>> any unused idle time to the hypervisor unless cpuidle is enabled.
>>>
>>> Thus is should default to y when pseries is enabled. I prefer that to
>>> a select so we can still make it modular if we want to.
>>>
>>> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
>>>
>>> ---
>>> Linus, do you want to just pick that up or should I put it into powerpc.git
>>> and ask you to pull ? I will have 2 or 3 other fixes there later today,
>>> but I wanted to make sure you were ok with the approach with this
>>> specific one.
>>
>> Hi, Ben.
>>
>> Note that building with CONFIG_PSERIES_IDLE=m fails.
>
> Ah ok. Well, making it built-in only makes sense anyway as I said
> separately, so I think I'll just select it.
>
> Cheers,
> Ben.
>
>> CC [M] arch/powerpc/platforms/pseries/processor_idle.o
>> arch/powerpc/platforms/pseries/processor_idle.c:35: error: redefinition
>> of ‘update_smt_snooze_delay’
>> /root/linux/arch/powerpc/include/asm/system.h:230: note: previous
>> definition of ‘update_smt_snooze_delay’ was here
>> arch/powerpc/platforms/pseries/processor_idle.c:175: error: redefinition
>> of ‘pseries_notify_cpuidle_add_cpu’
>> /root/linux/arch/powerpc/include/asm/system.h:231: note: previous
>> definition of ‘pseries_notify_cpuidle_add_cpu’ was here
>> make[2]: *** [arch/powerpc/platforms/pseries/processor_idle.o] Error 1
>> make[1]: *** [arch/powerpc/platforms/pseries] Error 2
>> make: *** [arch/powerpc/platforms] Error 2
>>
>> asm/system.h has empty inline implementations for
>> update_smt_snooze_delay and pseries_notify_cpuidle_add_cpu, which are
>> used when CONFIG_PSERIES_IDLE is undefined. Since those two functions
>> are used in core power architecture functions (store_smt_snooze_delay
>> at kernel/sysfs.c and smp_xics_setup_cpu at platforms/pseries/smp.c),
>> this requires some rework in these interactions or we should simply
>> disable PSERIES_IDLE to be built as a module for now.
>>
>> Regards.
>> Cascardo.
>>
>>>
>>> diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
>>> index 7dbc4a8..62ca70d 100644
>>> --- a/drivers/cpuidle/Kconfig
>>> +++ b/drivers/cpuidle/Kconfig
>>> @@ -1,7 +1,8 @@
>>>
>>> config CPU_IDLE
>>> bool "CPU idle PM support"
>>> - default ACPI
>>> + default y if ACPI
>>> + default y if PPC_PSERIES
>>> help
>>> CPU idle is a generic framework for supporting software-controlled
>>> idle processor power management. It includes modular cross-platform
The following patch disables pseries cpuidle driver to be loaded as a
module as there are build problems reported when one is trying to do so.
This is a work around for now until the problem is fixed.
arch/powerpc/platforms/pseries/Kconfig | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/Kconfig
b/arch/powerpc/platforms/pseries/Kconfig
index ae7b6d4..31f22c1 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -122,7 +122,7 @@ config DTL
Say N if you are unsure.
config PSERIES_IDLE
- tristate "Cpuidle driver for pSeries platforms"
+ bool "Cpuidle driver for pSeries platforms"
depends on CPU_IDLE
depends on PPC_PSERIES
default y
As pointed out, asm/system.h has empty inline implementations for
update_smt_snooze_delay and pseries_notify_cpuidle_add_cpu, which are
used when CONFIG_PSERIES_IDLE is undefined. Since those two functions
are used in core power architecture functions (store_smt_snooze_delay
at kernel/sysfs.c and smp_xics_setup_cpu at platforms/pseries/smp.c),
Going forward, the aim is to remove the dependency of using these
functions from core power architecture functions. So I am proposing the
following changes:
a) Removing update_smt_snooze_delay () and allow the pseries
idle backend driver to query snooze entry on need basis
while initializing the driver fields by exporting an api to return
snooze value for a given cpu.
b) Replacing the pseries_notify_cpuidle_add_cpu() call
by registering a cpu_notifier to take actions accordingly.
Regards,
Deepthi
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