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

[Elaine Zhang]

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.

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.

> > 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.
> >
> > May be I solution is not the optimal solution,Do you have better suggestion?
>
> Please see my comment above.
>
> [...]
>
> Kind regards
> Uffe