From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Dmitry Osipenko <digetx@gmail.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Lucas Stach <l.stach@pengutronix.de>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Krzysztof Kozlowski <krzk@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
peron.clem@gmail.com, Nishanth Menon <nm@ti.com>,
Stephen Boyd <sboyd@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Rafael Wysocki <rjw@rjwysocki.net>,
linux-samsung-soc@vger.kernel.org,
Chanwoo Choi <cw00.choi@samsung.com>
Subject: Re: [PATCH] regulator: do not balance regulators without constraints
Date: Fri, 29 May 2020 07:45:06 +0200 [thread overview]
Message-ID: <56e496bc-172f-d62f-5376-c8d734af6a51@samsung.com> (raw)
In-Reply-To: <20200528134338.GD3606@sirena.org.uk>
Hi Mark,
On 28.05.2020 15:43, Mark Brown wrote:
> On Thu, May 28, 2020 at 03:11:30PM +0200, Marek Szyprowski wrote:
>> Balancing coupled regulators must wait until the clients for all of the
>> coupled regualtors set their constraints, otherwise the balancing code
>> might change the voltage of the not-yet-constrained regulator to the
>> value below the bootloader-configured operation point, what might cause a
>> system crash.
> This forces every supply to have something which explicitly manages
> voltages which means that if one of the coupled supplies doesn't really
> care about the voltage (perhaps doesn't even have any explicit
> consumers) and just needs to be within a certain range of another supply
> then it'll end up restricting things needlessly.
Frankly, that's exactly what we need for Exynos5422 case. If devfreq
driver is not enabled/compiled, we want to keep the "vdd_int" volatage
unchanged. This confirms me that we really need to have a custom coupler
for Exynos5422 case. It will solve such issues without adding hacks to
regulator core.
> Saravana was trying to do some stuff with sync_state() which might be
> interesting here although I have concerns with that approach too:
>
> https://lore.kernel.org/lkml/20200527074057.246606-1-saravanak@google.com/
This still doesn't solve the above mentioned case.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
next prev parent reply other threads:[~2020-05-29 5:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200528131144eucas1p121b9151996fa3f780a5028f68c69d5ba@eucas1p1.samsung.com>
2020-05-28 13:11 ` [PATCH] regulator: do not balance regulators without constraints Marek Szyprowski
2020-05-28 13:43 ` Mark Brown
2020-05-29 5:45 ` Marek Szyprowski [this message]
2020-05-29 11:10 ` Mark Brown
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