Re: [PATCH v4 1/3] bus: simple-pm: add support to pm clocks

["Nayak, Rajendra" <rnayak@codeaurora.org>]

Hey Srini,

On 11/15/2016 4:55 PM, Srinivas Kandagatla wrote:
> + Rajendra (qcom,gdsc author)
[]..

>>
>>>> ---
>>>>  drivers/bus/simple-pm-bus.c | 13 ++++++++++++-
>>>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
>>>> index c5eb46c..63b7e8c 100644
>>>> --- a/drivers/bus/simple-pm-bus.c
>>>> +++ b/drivers/bus/simple-pm-bus.c
>>>> @@ -11,6 +11,7 @@
>>>>  #include <linux/module.h>
>>>>  #include <linux/of_platform.h>
>>>>  #include <linux/platform_device.h>
>>>> +#include <linux/pm_clock.h>
>>>>  #include <linux/pm_runtime.h>
>>>>
>>>>
>>>> @@ -22,17 +23,26 @@ static int simple_pm_bus_probe(struct
>>>> platform_device *pdev)
>>>>
>>>>       pm_runtime_enable(&pdev->dev);
>>>>
>>>> -     if (np)
>>>> +     if (np) {
>>>> +             of_pm_clk_add_clks(&pdev->dev);
>>
>> This should work out-of-the-box (that's the actual purpose of this
>> driver),
>> if the platform code that registers your PM Domain would take care
>> of registering the clocks needed for PM management of the bus.
>
> Yep, if the pm domain provider takes care of the bus clks, then it would
> work.
>
> Am guessing that the clocks property in the DT node would be read by the
> PM domain provider and enable/disable during attach/detach callbacks.
> If that is true, then any device tree nodes which are not children of
> "simple-pm-bus" and consumers of power-domain provider would enable all
> (including non-bus clks) clks twice. Once in the power-domain provider
> and once in the actual driver. Is this expected behavior from
> power-domains in general?
>
>>
>> Adding of_pm_clk_add_clks() here will start managing all clocks of the
>> bus,
>> which may not be wanted on all platforms.
>>
> That was the purpose.
>
>
> Rajendra,
> Looks like qcom gdsc pm domain provider driver does not handle bus clks
> along with power-domain, Is this something we should do? Or the bus
> driver take care of it?

I did post some patches to support handling of clocks associated with
gdscs [1], but it got dropped at that point since there wasn't a
real user, besides there were some open issues wrt the handling of
!CONFIG_PM cases etc.
I will revive and repost those patches again now based on the
discussions last time around.

[1] 
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-August/362492.html

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