Re: [PATCH v1 00/30] Introduce core voltage scaling for NVIDIA Tegra20/30 SoCs

[Dmitry Osipenko]

13.11.2020 17:45, Ulf Hansson пишет:
> On Thu, 12 Nov 2020 at 23:14, Dmitry Osipenko <digetx@xxxxxxxxx> wrote:
>>
>> 12.11.2020 23:43, Thierry Reding пишет:
>>>> The difference in comparison to using voltage regulator directly is
>>>> minimal, basically the core-supply phandle is replaced is replaced with
>>>> a power-domain phandle in a device tree.
>>> These new power-domain handles would have to be added to devices that
>>> potentially already have a power-domain handle, right? Isn't that going
>>> to cause issues? I vaguely recall that we already have multiple power
>>> domains for the XUSB controller and we have to jump through extra hoops
>>> to make that work.
>>
>> I modeled the core PD as a parent of the PMC sub-domains, which
>> presumably is a correct way to represent the domains topology.
>>
>> https://gist.github.com/digetx/dfd92c7f7e0aa6cef20403c4298088d7
> 
> That could make sense, it seems.
> 
> Anyway, this made me realize that
> dev_pm_genpd_set_performance_state(dev) returns -EINVAL, in case the
> device's genpd doesn't have the ->set_performance_state() assigned.
> This may not be correct. Instead we should likely consider an empty
> callback as okay and continue to walk the topology upwards to the
> parent domain, etc.
> 
> Just wanted to point this out. I intend to post a patch as soon as I
> can for this.

Thank you, I was also going to make the same change, but haven't
bothered to do it so far. Please feel free to CC me on the patch.