Re: [PATCH] soc: rockchip: power-domain: remove PM clocks

[Geert Uytterhoeven]

Hi Tomasz,

On Wed, Feb 28, 2018 at 1:29 PM, Tomasz Figa <tfiga@xxxxxxxxxxxx> wrote:
> On Wed, Feb 28, 2018 at 9:17 PM, Geert Uytterhoeven
> <geert@xxxxxxxxxxxxxx> wrote:
>> On Wed, Feb 28, 2018 at 12:11 PM, Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx> wrote:
>>> Currently we are adding all of the attached devices' clocks as pm clocks
>>> and enable them when powering on the power domain.
>>>
>>> This seems unnecessary, because those clocks are already controlled in
>>> the devices' drivers with better error handling.
>>>
>>> Tested on my chromebook minnie(rk3288) and chromebook kevin(rk3399).
>>>
>>> Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
>>
>> Thanks for your patch!
>>
>> Just wondering: so you prefer to handle the clocks explicitly in all drivers,
>> instead of delegating this task to Runtime PM?
>
> Is it already possible to gate clocks immediately when the device
> idles, but defer turning the power domain off until time long enough
> to cover the power down and up latency elapses?

I'm not 100% sure.
Note that clocks are turned off when the device idles, while powering down
the power domain requires all devices in the domain to be idle.

> Also, how about systems where runtime PM is disabled? I think that's
> one of the reasons we control the clocks explicitly in the drivers
> anyway.

On many platforms, Runtime PM is always enabled.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds