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

[Elaine Zhang]

On 02/06/2017 08:46 PM, Ulf Hansson wrote:
> On 5 February 2017 at 10:34, Elaine Zhang <zhangqing@xxxxxxxxxxxxxx> wrote:
> > On 01/26/2017 05:30 AM, Ulf Hansson wrote:
> > > On 22 January 2017 at 04:34, Elaine Zhang <zhangqing@xxxxxxxxxxxxxx>
> > > wrote:
> > > > On 01/20/2017 09:16 PM, Ulf Hansson wrote:
> > > > > On 20 January 2017 at 03:21, Elaine Zhang <zhangqing@xxxxxxxxxxxxxx>
> > > > > wrote:
> > > > > > If a PM domain is powered off before system suspend,
> > > > > > we hope do nothing in system runtime suspend noirq phase
> > > > > > and system runtime resume noirq phase.
> > > > >
> > > > >
> > > > >
> > > > > One can hope, but that isn't good enough. :-)
> > > > >
> > > > >
> > > > > > This modify is to slove system resume issue for RK3399.
> > > > > > RK3399 SOC pd_gpu have voltage domain vdd_gpu,
> > > > > > so we must follow open vdd_gpu and power on pd_gpu,
> > > > > > power off pd_gpu and disable vdd_gpu.
> > > > > > Fix up in runtime resume noirq phase power on all PDs.
> > > > >
> > > > >
> > > > >
> > > > > This doesn't make any sense to me. Can please try to explain this is
> > > > > in great more detail, then I can try to help.
> > > > For example:
> > > > -->device suspend
> > > >      (mali gpu driver set pd_gpu off by pm_runtime_put_sync(),
> > >
> > >
> > > This is the wrong approach, as runtime suspend is prevented by the PM
> > > core in this phase. More precisely, it does a
> > > pm_runtime_get_noresume() in the device prepare phase.
> > >
> > > I think it seems like you would benefit from using the so called the
> > > runtime PM centric approach, which gives you system PM support for
> > > "free". Please have a look at the pm_runtime_force_suspend|resume()
> > > helpers.
> > >
> > > >       and then disabled the vdd_gpu by regulator_disable().)
> > > >           --> system suspend
> > > >                   -->prepare
> > > >                           -->suspend_noirq():
> > > >                           (power off all pds)
> > > >           -->system resume
> > > >                   -->resume_noirq():
> > > >                   (power up all pds)
> > > >                   (in this case the vdd_gpu is still disabled,
> > > >                    if power on the pd_gpu maybe make the system crash)
> > > >           -->complete : power off the not used pd
> > > > -->device resuem
> > > >      (mali gpu driver enable vdd_gpu by regulator_enable(),
> > > >       and then power up the pd_gpu by pm_runtime_get_sync())
> > >
> > >
> > > Seems like there is also a missing configuration of the relationship
> > > between the PM domains. In the genpd terminology, you probably want to
> > > set pd_gpu as a subdomain of the vdd_gpu.
> > >
> > > In that way, the vdd_gpu is always powered on before pd_gpu is powered
> > > on. And vice verse when powering off.
> > I thought about this project, but can't slove the problem of sleep and wakp
> > up issue.
> > Because
> >          -->system resume
> >                   -->resume_noirq():
> >                    (power up all pds)
> > In this case, we set pd_gpu as a subdomain of the vdd_gpu.
> > And then to enable the vdd_gpu,but the system resume is not complete yet,
> > the regulator and i2c can't work.So the vdd_gpu enable will failed.
>
> Okay, I see.
>
> > So I think the more appropriate solution is keep the pd status during system
> > PM phases.
> > If a PM domain is powered off before system suspend,
> > we hope do nothing in system runtime suspend noirq phase
> > and system runtime resume noirq phase.
>
> 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.

> 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).

> 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
> > > > So for RK3399 soc, if to set pd_gpu the vdd_gpu must be enabled, or else
> > > > will can't get the ack back.
> > > > I hope the pd_gpu power up/off by the driver itself.
>
> [...]
>
> Kind regards
> Uffe