Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 5 Aug 2021 14:08:42 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Peter Geis <pgwipeout@gmail.com>
Cc:     Jaehoon Chung <jh80.chung@samsung.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Rob Herring <robh+dt@kernel.org>, linux-mmc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        devicetree@vger.kernel.org
Subject: Re: [BUG] mmc_regulator_set_ocr can't cope with regulator-fixed
Message-ID: <20210805130842.GO26252@sirena.org.uk>
References: <CGME20210804143357epcas1p1c67eca591d8bb557c11b8175baaa8550@epcas1p1.samsung.com>
 <CAMdYzYrx8pgeyK7u=kcopZ+Wae+fQdr_uM4AuVjqWKfZYikgcA@mail.gmail.com>
 <a9aa636e-326f-a848-dd69-41df87c013af@samsung.com>
 <CAMdYzYr9PX-9=kkCAfGe8Q0-D+gRo_qCwse8SiGVsmod7fffiA@mail.gmail.com>
 <20210805124650.GM26252@sirena.org.uk>
 <CAMdYzYpR6br7s1RD2ze92WzJjtEDZwy9qS6YhghgXy7F91keFg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="eHmdSDY+kY2au76U"
Content-Disposition: inline
In-Reply-To: <CAMdYzYpR6br7s1RD2ze92WzJjtEDZwy9qS6YhghgXy7F91keFg@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk


--eHmdSDY+kY2au76U
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

On Thu, Aug 05, 2021 at 08:58:58AM -0400, Peter Geis wrote:
> On Thu, Aug 5, 2021 at 8:47 AM Mark Brown <broonie@kernel.org> wrote:

> > One thing to watch out for with this approach is if there's things that
> > really need a specific voltage to be set then you'll have to stop those
> > things happening if you've got a voltage regulator that can't deliver a
> > voltage in the required range.  I don't know if this affects MMC or not,
> > if it's just a case of being less efficient it's not such an issue.

> Yeah, but if this is a fixed regulator and it's a problem, then the
> hardware is screwed anyways.

Well, the fact that the voltage is being changed at runtime indicates
that we're changing something from whatever was in the fixed setup - it
can sometimes be that we don't have access to some higher performance or
lower power features for example.  That's not ideal but works perfectly
safely.

--eHmdSDY+kY2au76U
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmEL4tkACgkQJNaLcl1U
h9Dbbgf/YunQb1UPyQ5czRyhW+fldplspxf07rcnSp/hwj2hV4FLvf9wzXk5thAp
vDMEhO16kYSmm7sgZgnwXrk6BdBcyznZReLOKvKRi4tL+ce9niWYlTaucGhJDdN+
tEFhB2q2wQx69UpWm0HzCkT2aZG1bi40plL7Y51UQGw5VmsbhigEwiLLQFBHsL6m
yn5/AksIgxD2zxHPx0N2CW/7CxzlLixhJYxNoZoCuWYR1YptFlOzqlL8NyftQ/kH
bi27Ep0qc3quoiIULpybE66b/0r6xFvNqWQ393La436az1KM5p10R5bNkT44bOWw
scag4eXxevkgaU0RgEUI0hQHq5zuHw==
=+zJO
-----END PGP SIGNATURE-----

--eHmdSDY+kY2au76U--