linux-kernel - Re: [BUG] mmc_regulator_set_ocr can't cope with regulator-fixed

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Message-ID: <20210805130842.GO26252@sirena.org.uk>
Date:   Thu, 5 Aug 2021 14:08:42 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Peter Geis <pgwipeout@...il.com>
Cc:     Jaehoon Chung <jh80.chung@...sung.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>, linux-mmc@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        devicetree@...r.kernel.org
Subject: Re: [BUG] mmc_regulator_set_ocr can't cope with regulator-fixed

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@...nel.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.

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