linux-kernel - Re: [PATCH] arm64: dts: imx8mm-kontron-n801x-som: do not allow to switch off buck2

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Message-ID: <898fd5e0-2073-3689-89b6-2c5071773786@kontron.de>
Date:   Wed, 15 Sep 2021 14:09:06 +0200
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Michael Walle <michael@...le.cc>,
        Heiko Thiery <heiko.thiery@...il.com>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Joakim Zhang <qiangqing.zhang@....com>,
        Shengjiu Wang <shengjiu.wang@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Subject: Re: [PATCH] arm64: dts: imx8mm-kontron-n801x-som: do not allow to
 switch off buck2

On 15.09.21 14:05, Michael Walle wrote:
> Am 2021-09-15 14:03, schrieb Heiko Thiery:
>> The buck2 output of the PMIC is the VDD core voltage of the cpu.
>> Switching off this will poweroff the CPU. Add the 'regulator-always-on'
>> property to avoid this.
> 
> Mh, have this ever worked? Is there a commit which introduced a regression?

Yes, this did work before, even without 'regulator-always-on'. I
currently don't understand why this is needed. The regulator is
referenced in the CPU nodes as 'cpu-supply'. This should be enough to
not disable it as long as the CPU is up.