Re: Attempted summary of suspend-blockers LKML thread

david
2010-08-04T23:39:58Z

On Thu, 5 Aug 2010, Rafael J. Wysocki wrote:

> On Thursday, August 05, 2010, david@lang.hm wrote:
>> On Wed, 4 Aug 2010, Rafael J. Wysocki wrote:
>>
>>> Subject: Re: Attempted summary of suspend-blockers LKML thread
>>>
>>> On Wednesday, August 04, 2010, david@lang.hm wrote:
>>>> On Wed, 4 Aug 2010, Rafael J. Wysocki wrote:
>>>>> In the suspend case, when you have frozen all applications, you can
>>>>> sequentially disable all interrupts except for a few selected ("wakeup") ones
>>>>> in a safe way. By disabling them, you ensure that the CPU will only be
>>>>> "revived" by a limited set of events and that allows the system to stay
>>>>> low-power for extended time intervals.
>>>>
>>>> the benifit of this will depend on what wakeups you are able to avoid by
>>>> putting the hardware to sleep. Depending on the hardware, this may be not
>>>> matter that much.
>>>
>>> That's correct, but evidently it does make a difference with the hardware
>>> Android commonly runs on.
>>
>> Ok, but is there a way to put some of this to sleep without involving a
>> full suspend?
>
> Technically, maybe, but we have no generic infrastructure in the kernel for that.
> There may be SoC-specific implementations, but nothing general enough.

well, I know that we have specific cases of this (drive spin-down, cpu
speed, display backlight for a few examples), is it worth trying to define
a generic way to do this sort of thing? or should it be left as a
per-device thing (with per-device knobs to control it)

I thought I had seen discussion on how to define such a generic power
management interface, and I thought the results had been acceptable.

David Lang