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Date:   Tue, 14 Sep 2021 10:32:26 +0200
From:   Michael Walle <michael@walle.cc>
To:     Lucas Stach <l.stach@pengutronix.de>
Cc:     Heiko Thiery <heiko.thiery@gmail.com>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Fabio Estevam <festevam@gmail.com>,
        Shengjiu Wang <shengjiu.wang@nxp.com>,
        Joakim Zhang <qiangqing.zhang@nxp.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>
Subject: Re: [PATCH v2] arm64: dts: imx8mq-kontron-pitx-imx8m: remove
 vqmmc-supply node
In-Reply-To: <449f718706fd5af03190bdda986de37aa8fa14e3.camel@pengutronix.de>
References: <20210914072627.24173-1-heiko.thiery@gmail.com>
 <449f718706fd5af03190bdda986de37aa8fa14e3.camel@pengutronix.de>
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Hi Lucas,

Am 2021-09-14 10:20, schrieb Lucas Stach:
> Am Dienstag, dem 14.09.2021 um 09:26 +0200 schrieb Heiko Thiery:
>> The sw4 output (V_1V8_S0 voltage) from the PMIC is the main supply for
>> the 1V8 power domain. It is not only used as supply for the eMMC.
>> So this voltage can not be changed and is not allowed to switched off.
>> Therefore we do not want to provide this regulator to the SDHC driver 
>> to
>> control this voltage.
>> 
> This specific requirement should not be solved by removing the
> regulator connection from the SDHCI node, but instead by constraining
> the regulator voltage range to a fixed 3.3V and marking the regulator
> as always-on to reflect the hardware requirements in the DT.
> 
> Also if your eMMC vqmmc is a fixed 3.3V, I don't think you need the
> faster pinctrl states, as you can't use the faster pin states anyways,
> as they require a 1.8V signaling voltage.

Are you speaking of the 1.8V signalling modes? As far as I know the
IMX SDHC controller will switch the voltage by its own function pin.
That is, its not a GPIO.

-michael