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    SubjectRe: [PATCH 3/3] arm64: dts: mediatek: mt8365-pumpkin: Add overlays for thp7312 cameras
    On Wed, Sep 06, 2023 at 12:01:43PM +0100, Kieran Bingham wrote:
    > Quoting Laurent Pinchart (2023-09-06 10:35:31)
    > > On Wed, Sep 06, 2023 at 11:21:31AM +0200, Krzysztof Kozlowski wrote:
    > > > On 06/09/2023 11:00, Laurent Pinchart wrote:
    > > > >>> has a regulator@0. There are similar instances for clocks.
    > > > >>>
    > > > >>> I understand why it may not be a good idea, and how the root node is
    > > > >>> indeed not a bus. In some cases, those regulators and clocks are grouped
    > > > >>> in a regulators or clocks node that has a "simple-bus" compatible. I'm
    > > > >>> not sure if that's a good idea, but at least it should validate.
    > > > >>>
    > > > >>> What's the best practice for discrete board-level clocks and regulators
    > > > >>> in overlays ? How do we ensure that their node name will not conflict
    > > > >>> with the board to which the overlay is attached ?
    > > > >>
    > > > >> Top-level nodes (so under /) do not have unit addresses. If they have -
    > > > >> it's an error, because it is not a bus. Also, unit address requires reg.
    > > > >> No reg? No unit address. DTC reports this as warnings as well.
    > > > >
    > > > > I agree with all that, but what's the recommended practice to add
    > > > > top-level clocks and regulators in overlays, in a way that avoids
    > > > > namespace clashes with the base board ?
    > > >
    > > > Whether you use regulator@0 or regulator-0, you have the same chances of
    > > > clash.
    > >
    > > No disagreement there. My question is whether there's a recommended
    > > practice to avoid clashes, or if it's an unsolved problem that gets
    > > ignored for now because there's only 36h in a day and there are more
    > > urgent things to do.
    >
    > Should an overlay add these items to a simple-bus specific to that
    > overlay/device that is being supported?
    >
    > That would 'namespace' the added fixed-clocks/fixed-regulators etc...
    >
    > But maybe it's overengineering or mis-using the simple-bus.

    You would still need to name the node that groups the regulators and
    clocks in a way that wouldn't clash between multiple overlays and the
    base board. It would be nice to have nodes that are "private" to an
    overlay.

    > And the items are still not on a 'bus' with an address - they just exist
    > on a presumably externally provided board....

    --
    Regards,

    Laurent Pinchart

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