12.11.2020 23:43, Thierry Reding пишет:

quoted

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

quoted

The only thing which makes me feel a bit uncomfortable is that there is
no real hardware node for the power domain node in a device-tree.

Could we anchor the new power domain at the PMC for example? That would
allow us to avoid the "virtual" node.

I had a thought about using PMC for the core domain, but not sure
whether it will be an entirely correct hardware description. Although,
it will be nice to have it this way.

This is what Tegra TRM says about PMC:

"The Power Management Controller (PMC) block interacts with an external
or Power Manager Unit (PMU). The PMC mostly controls the entry and exit
of the system from different sleep modes. It provides power-gating
controllers for SOC and CPU power-islands and also provides scratch
storage to save some of the context during sleep modes (when CPU and/or
SOC power rails are off). Additionally, PMC interacts with the external
Power Manager Unit (PMU)."

The core voltage regulator is a part of the PMU.

Not all core SoC devices are behind PMC, IIUC.

On the other hand, if we were to
use a regulator, we'd be adding a node for that, right? So isn't this
effectively going to be the same node if we use a power domain? Both
software constructs are using the same voltage regulator, so they should
be able to be described by the same device tree node, shouldn't they?

I'm not exactly sure what you're meaning by "use a regulator" and "we'd
be adding a node for that", could you please clarify? This v1 approach
uses a core-supply phandle (i.e. regulator is used), it doesn't require
extra nodes.