linux-kernel - Re: [PATCH] arm64: dts: imx8mp-verdin: board regulators: add always-on

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Message-ID: <20220902125040.GA5699@francesco-nb.int.toradex.com>
Date:   Fri, 2 Sep 2022 14:50:40 +0200
From:   Francesco Dolcini <francesco.dolcini@...adex.com>
To:     Mark Brown <broonie@...nel.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Max Krummenacher <max.oss.09@...il.com>
Cc:     Max Krummenacher <max.krummenacher@...adex.com>,
        Fabio Estevam <festevam@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Rob Herring <robh+dt@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH] arm64: dts: imx8mp-verdin: board regulators: add
 always-on

On Thu, Sep 01, 2022 at 07:44:43PM +0100, Mark Brown wrote:
> On Thu, Sep 01, 2022 at 09:29:13PM +0300, Laurent Pinchart wrote:
> > On Thu, Sep 01, 2022 at 01:04:22PM +0200, Max Krummenacher wrote:
> > > From: Max Krummenacher <max.krummenacher@...adex.com>
> 
> > > These regulators are switched on by HW during power up and can not
> > > be influenced by SW.
> > > Set the always-on property.
> > 
> > Is this needed ? When a fixed regulator has no control GPIO or clock, as
> > is the case here, I would expect the driver and/or regulator core to
> > understand that it's always on, as the alternative is always-off, which
> > is pointless :-) Mark, Liam, what do you think ?
> 
> If there's no physical control setting always-on does nothing.

The patch was posted because of a warning on trying to disable an unused
regulator.

However this was changed with
  261f06315cf7 ("regulator: Flag uncontrollable regulators as always_on").

Max was testing with a kernel without this patch in and forgot to verify
on latest upstream kernel.

Just disregard this.

Francesco