Re: [PATCH v2] PM / Domains: Keep the pd status during system PM phases

[Elaine Zhang]

On 02/07/2017 04:19 PM, Ulf Hansson wrote:
> [...]
>
> > > Unfortunate, I am still not fully understanding the scenarios. As you
> > > indicate, the problem seems related to wakeup settings.
> > >
> > > Could you please try to answer the below questions, hopefully it helps
> > > me to better understand.
> > >
> > > 1)
> > > While starting the system suspend sequence, under what circumstances
> > > are you expecting the vdd_gpu and pd_gpu to be powered on?
> >
> > I don't want to power on the vdd_gpu and pd_gpu during the system suspend
> > sequence.
> > I hope the pd_gpu and vdd_gpu power on/off just by gpu device.
>
> Let me rephrase my question.
>
> Can the vdd_gpu/pd_gpu ever remain in a powered on state while the
> system is suspended?
NO, the vdd_gpu/pd_gpu ever remain in a powered off state while the
system is suspended.
> If yes, when is that the case?
>
> > > 2)
> > > While starting the system suspend sequence, under what circumstances
> > > are you expecting the vdd_gpu and the pd_gpu to be powered off?
> >
> > I don't want to power off the vdd_gpu and pd_gpu during the system suspend
> > sequence.
> > Because before the system suspend,the vdd_gpu and pd_gpu has been power off
> > by gpu device(pm_ruantime_put).
>
> *Exactly*, how do you guarantee that a pm_runtime_put() for the gpu
> device triggers a runtime suspend - before a system suspend sequence
> starts?
>
> For example, userspace may via sysfs prevent runtime suspend for any
> device with runtime PM enabled.
Yes, you are right.I did't consider this.
Whether on or off pd_gpu, the vdd_gpu is must be enabled.How to deal 
with the enable/disable the vdd_gpu?

our process in devices/platform/ff9a0000.gpu:
device init
	pm_runtime_enable()

gpu_power_on
	regulator_enable(vdd_gpu)
	pm_runtime_get_sync(pd_gpu)

gpu_power_off
	pm_runtime_put_sync(pd_gpu)
	regulator_disable(vdd_gpu)

device remove
	pm_runtime_disable()

> > > 3)
> > > What devices are attached to vdd_gpu?
> > just pd_gpu
> > > 4)
> > > What devices are attached to pd_gpu?
> > just gpu device(mali driver)
> >
> > vdd_gpu
> > ------- pd_gpu
> > ----------------devices/platform/ff9a0000.gpu
> > >
>
> Thanks for these details, very useful!
>
> [...]
>
> Kind regards
> Uffe