Re: [PATCH 1/2] ARM: s3c64xx: cpuidle: convert to platform driver

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 10/30/2013 03:40 PM, Tomasz Figa wrote:
> Hi Daniel,
>
> On Wednesday 30 of October 2013 14:43:51 Daniel Lezcano wrote:
>> On 10/25/2013 03:23 PM, Daniel Lezcano wrote:
>>
>> [ ... ]
>>
>>>>> Won't it be worth to add a new WFI_SLEEP state to the cpuidle driver
>>>>> ?
>>>>
>>>> I don't think so. How a suspend-to-RAM specific thing like WFI_SLEEP
>>>> could
>>>> be relevant to a cpuidle driver? (Unless there are some plans to
>>>> consolidate STR with cpuidle that I haven't heard about...)
>>>
>>> I finally found a documentation for the s3c6410x and the description
>>> of
>>> the different modes. Indeed, the sleep mode is not adequate for a
>>> cpuidle state. What about the 'stop' and 'deep stop' state ?
>>
>> Hi Thomas,
>>
>> just a reminder about the question above, so I can go ahead: fix what
>> you pointed out or remove the driver directly.
>>
>> You mentionned in the previous email the STOP is not usful because it
>> can be controlled by manually outside of the cpuidle driver. But I see
>> in the documentation, the stop states power gates the cpu and deep-stop
>> stops the regulator.
>
> STOP clock-gates the CPU and DEEP-STOP power-gates it by stopping the
> regulator.
>
> There are some interesting aspects of those modes, like memory self-
> refresh, PLL power-off and system-wide down clocking, but I believe they
> are too tricky to handle (coupling with device PM, stopped timers) and
> with too little possible power saving to justify the effort of adding
> support for them.
>
> In the end, I haven't seen support for them implemented even in strange
> vendor kernels used even on production devices, like Android phones.
>
>>
>> If these states have to been added later, still it worth to remove the
>> driver ?
>
> I don't think that anybody is even going to add support for them and by
> anybody I should probably mean myself, since I'm currently the only person
> actively adding new code for this platform, as a part of my hobby.

Ok, I will kill the driver then.

Thanks
   -- Daniel


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