On Wed, 2022-06-15 at 10:37 -0700, Krzysztof Kozlowski wrote: > On 15/06/2022 10:31, Marcel Ziswiler wrote: > > Hi > > > > On Wed, 2022-06-15 at 10:15 -0700, Krzysztof Kozlowski wrote: > > > On 15/06/2022 09:10, Max Krummenacher wrote: > > > > Hi > > > > > > > > On Tue, Jun 14, 2022 at 9:22 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > > > > > > > > > Hi Rob, > > > > > > > > > > On Mon, Jun 13, 2022 at 9:15 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > > On Thu, Jun 09, 2022 at 05:08:46PM +0200, Max Krummenacher wrote: > > > > > > > From: Max Krummenacher <max.krummenacher@xxxxxxxxxxx> > > > > > > > > > > > > > > its power enable by using a regulator. > > > > > > > > > > > > > > The currently implemented PM domain providers are all specific to > > > > > > > a particular system on chip. > > > > > > > > > > > > Yes, power domains tend to be specific to an SoC... 'power-domains' is > > > > > > supposed to be power islands in a chip. Linux 'PM domains' can be > > > > > > anything... > > > > > > > > I don't see why such power islands should be restricted to a SoC. You can > > > > build the exact same idea on a PCB or even more modular designs. > > > > > > In the SoC these power islands are more-or-less defined. These are real > > > regions gated by some control knob. > > > > > > Calling few devices on a board "power domain" does not make it a power > > > domain. There is no grouping, there is no control knob. > > > > > > Aren't you now re-implementing regulator supplies? How is this different > > > than existing supplies? > > > > I believe the biggest difference between power-domains and regulator-supplies lays in the former being > > driver > > agnostic while the later is driver specific. > > That's one way to look, but the other way (matching the bindings > purpose) is to look at hardware. You have physical wire / voltage rail > supply - use regulator supply. In the terms of the hardware - what is > that power domain? It's a concept, not a physical object. Well, but how can that concept then exist within the SoC but not outside? I don't get it. Isn't it just the exact same physical power gating thingy whether inside the SoC or on a PCB? > > Meaning with power-domains one can just add such arbitrary > > structure to the device tree without any further driver specific changes/handling required. While with > > regulator-supplies each and every driver actually needs to have driver specific handling thereof added. Or > > do I > > miss anything? > > Thanks for clarification but I am not sure if it matches the purpose of > bindings and DTS. You can change the implementation as well to have > implicit regulators. No need for new bindings for that. Okay, maybe that would also work, of course. So basically add a new binding which allows adding regulators to arbitrary nodes which then will be generically handled by e.g. runtime PM. Almost something like assigned- clocks [1] you mean? I guess that could work. Remember that's why Max posted it as an RFC to get such feedback. Thanks for further refining those ideas. > > We are really trying to model something where a single GPIO pin (via a GPIO regulator or whatever) can > > control > > power to a variety of on-board peripherals. And, of course, we envision runtime PM actually making use of > > it > > e.g. when doing suspend/resume. > > And this GPIO pin controls what? Some power switch which cuts the power > of one regulator or many? Well, that doesn't really matter. Resp. this part one should be able to sufficiently model using whatever available regulator lore we already have (e.g. whatever delays/times). > If many different regulators, how do you > handle small differences in ramp up time? Well, I don't think this is any different to any other regulator(s), not? Them HW folks will just need to tell us some reasonable numbers for those delays/times. > Best regards, > Krzysztof [1] https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/clock/clock.yaml#L22 Cheers Marcel
