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

From: Ulf Hansson
Date: Wed Jan 25 2017 - 16:30:29 EST

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()

> 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.

> 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