[linux-pm] [PATCH 1/3 v3] ARM: EXYNOS4: Support for generic I/O power domains on EXYNOS4210/4212

[Kyungmin Park]

On 11/15/11, Kukjin Kim <kgene.kim at samsung.com> wrote:
> Chanwoo Choi wrote:
>> Hi Kukjin Kim,
>>
>> Please reply about Sylwester Nawrocki and me.
>> 2011/11/3 Sylwester Nawrocki <s.nawrocki at samsung.com>
>> Hi Kgene,
>>
>> On 11/03/2011 03:09 AM, Kukjin Kim wrote:
>> > As I said, I don't think we should control/gate the clocks with
> regarding power domain.
>> As far as I know there is a plan to let the drivers override
> start/stop_device callbacks,
>> moreover the clock control can be disabled globally by not implementing
> start/stop_device
>> callbacks or per device by not adding clkdev entities to the device clock
> list at runtime
>> PM core. So IMHO, there is/going to be enough flexibility.
>>
>> > It should be controlled by each regarding device driver and in addition,
> as I know,
>> > to handle block of clock is not recommended on EXYNOS4 now.
>> What do you mean by this ? I couldn't find such information in any
> documentation.
>> Shouldn't "clock gate block" registers be touched by boot loader and the
> kernel?
>> Our boot loaders disable all clocks, and if the global clock gate is not
> enabled
>> by the kernel there is no chance any multimedia device will work.
>>
>> Should the global clock block gate be always enabled then ? I'm afraid it
> is not
>> optimal form power management POV.
>>
> Sylwester, let me check again before replying.
>
>> To Kukjin Kim,
>>
> Hi Chanwoo,
>
> Firstly, please use text-typed e-mail when you reply.
>
>> > It should be controlled by each regarding device driver and in addition,
> as I know,
>> > to handle block of clock is not recommended on EXYNOS4 now.
>>
>> As you said, should we separately control power and clock of power domain?
>
> If you ask my opinion, yes, I mean when it is required, it would be
> controlled independent.

Okay. It's meaning-less, Until change his mind, just drop it. I hope
you don't change this mind for long time.

Thank you,
Kyungmin Park
>
>> or Have to turn on the clock of power domain always?
>
> I didn't say like that.
>
>> I think that it is to happen unnecessary power consumption.
>
> I don't think, when the power of block/domain is downed, does it happen
> _really_ meaningful power consumption?
>
>> If we have to maintain on state of power domain clock, please let me know
> guide about this.
>>
>> Also,
>> For example, fimg2d and framebuffer use LCD0 power domain as parent
> device.I
>> If fimg2d and framebuffer is disabled state due to not using their,
>> I think that we should turn off the clock of LCD0 power domain to reduce
> power leakage.
>
> I think, probably it doesn't matter. If any useful data, please let me know.
>
>> Which each regarding device driver control the clock of power domain?
>>
>> I will expect for your reply.
>>
>
> Thanks.
>
> Best regards,
> Kgene.
> --
> Kukjin Kim <kgene.kim at samsung.com>, Senior Engineer,
> SW Solution Development Team, Samsung Electronics Co., Ltd.
>
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