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SubjectRe: [PATCH] regulator: core: Clean enabling always-on regulators + their supplies
On Thu, Dec 06, 2018 at 02:23:18PM -0800, Douglas Anderson wrote:
> At the end of regulator_resolve_supply() we have historically turned
> on our supply in some cases. This could be for one of two reasons:
>
> 1. If resolving supplies was happening before the call to
> set_machine_constraints() we needed to predict if
> set_machine_constraints() was going to turn the regulator on and we
> needed to preemptively turn the supply on.
> 2. Maybe set_machine_constraints() happened before we could resolve
> supplies (because we failed the first time to resolve) and thus we
> might need to propagate an enable that already happened up to our
> supply.
>
> Historically regulator_resolve_supply() used _regulator_is_enabled()
> to decide whether to turn on the supply.
>
> Let's change things a little bit. Specifically:
>
> 1. Let's try to enable the supply and the regulator in the same place,
> both in set_machine_constraints(). This means that we have exactly
> the same logic for enabling the supply and the regulator.
> 2. Let's properly set use_count when we enable always-on or boot-on
> regulators even for those that don't have supplies. The previous
> commit 1fc12b05895e ("regulator: core: Avoid propagating to
> supplies when possible") only did this right for regulators with
> supplies.
> 3. Let's make it clear that the only time we need to enable the supply
> in regulator_resolve_supply() is if the main regulator is currently
> in use. By using use_count (like the rest of the code) to decide
> if we're going to enable our supply we keep everything consistent.
>
> Overall the new scheme should be cleaner and easier to reason about.
> In addition to fixing regulator_summary to be more correct (because of
> the more correct use_count), this change also has the effect of no
> longer using _regulator_is_enabled() in this code path.
> _regulator_is_enabled() could return an error code for some regulators
> at bootup (like RPMh) that can't read their initial state. While one
> can argue that the design of those regulators is sub-optimal, the new
> logic sidesteps this brokenness. This fix in particular fixes
> observed problems on Qualcomm sdm845 boards which use the
> above-mentioned RPMh regulator. Those problems were made worse by
> commit 1fc12b05895e ("regulator: core: Avoid propagating to supplies
> when possible") because now we'd think at bootup that the SD
> regulators were already enabled and we'd never try them again.
>
> Fixes: 1fc12b05895e ("regulator: core: Avoid propagating to supplies when possible")
> Reported-by: Evan Green <evgreen@chromium.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Looks good on the Nexus 5 (qcom msm8974).

Tested-by: Brian Masney <masneyb@onstation.org>

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