Messages in this thread | | | Date | Wed, 15 Jun 2022 21:48:52 +0300 | Subject | Re: [PATCH v1 0/5] power: domain: Add driver for a PM domain provider which controls | From | Dmitry Baryshkov <> |
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On 15/06/2022 21:13, Marcel Ziswiler wrote: > 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@linux-m68k.org> wrote: >>>>>> >>>>>> Hi Rob, >>>>>> >>>>>> On Mon, Jun 13, 2022 at 9:15 PM Rob Herring <robh@kernel.org> wrote: >>>>>>> On Thu, Jun 09, 2022 at 05:08:46PM +0200, Max Krummenacher wrote: >>>>>>>> From: Max Krummenacher <max.krummenacher@toradex.com> >>>>>>>> >>>>>>>> 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.
Please do not do this. You have an external device. It has some input voltage rails. Please define -supply properties for each of the voltage rails. Explicitly power them on and off. Use fixed-regulator for your GPIO regulators. Other boards might have other ways to control the power supply.
Then define the pm_runtime callbacks doing proper work for you. If you wish to do the magic, consider looking on the pm_clock.h interface (and adding the pm_regulators.h). But this approach can also be frowned upon by the PM maintainers. Nevertheless, this is the driver/core issue. The DT interface should be the same: a set of regulators and a set of -supply properties.
-- With best wishes Dmitry
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