From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Masney Subject: Re: [PATCH] regulator: core: Clean enabling always-on regulators + their supplies Date: Thu, 6 Dec 2018 20:31:01 -0500 Message-ID: <20181207013101.GA27539@basecamp> References: <20181206222318.240401-1-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181206222318.240401-1-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Douglas Anderson Cc: Mark Brown , linux-arm-msm@vger.kernel.org, Dmitry Osipenko , evgreen@chromium.org, Liam Girdwood , linux-kernel@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org 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 > Signed-off-by: Douglas Anderson Looks good on the Nexus 5 (qcom msm8974). Tested-by: Brian Masney