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    SubjectRe: [PATCH RFC 1/2] regulator: core: Disable unused regulators with unknown status
    On Tue, Oct 24, 2023 at 10:57:38AM +0200, Stephan Gerhold wrote:

    > I think it does not change much for this patch, though. Even when
    > implemented in the core we still need to represent this situation
    > somehow for regulator_is_enabled(). Simply returning 0 (disabled) or
    > 1 (enabled) would be wrong. Do you think returning -EBUSY would be
    > appropriate for that?

    In these cases where we simply can't read the expectation is that we'll
    always be using the logical state - one way of thinking about it is that
    the operation is mostly a bootstrapping helper to figure out what the
    initial state is. A quick survey of users suggest they'll pretty much
    all be buggy if we start returning errors, and I frankly even if all the
    current users were fixed I'd expect that to continue to be a common
    error. I suppose that the effect of ignoring the possibility of error
    is like the current behaviour though.

    > The second challenge I see on a quick look is that both
    > qcom_smd-regulator.c and qcom-rpmh-regulator.c use their reference
    > counter internally in other function (e.g. to decide if a voltage change
    > should be sent, see "vreg->enabled" checks). I think we would also need
    > to add some rdev_is_enabled() function that would expose the core
    > reference counter to the driver?

    > Tracking the enable state in the driver (the way it is right now) is not
    > that much code, so I'm not entirely sure if we might actually end up
    > with more code/complexity when moving this to the core.

    We have to do the reference count in the core anyway since it's a
    reference count not just a simple on/off so it doesn't really cost us
    anything to make it available to drivers.
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