linux-kernel - Re: [PATCH 5/7] arm64: dts: tegra210-p2180: Allow ldo2 to go down to 1.8 V

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Message-ID: <2bb6f4a6-5f5d-0ab6-ae62-169bd03739ca@kapsi.fi>
Date:   Wed, 25 Jul 2018 09:50:59 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Aapo Vienamo <avienamo@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mikko Perttunen <mperttunen@...dia.com>
Cc:     linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] arm64: dts: tegra210-p2180: Allow ldo2 to go down to
 1.8 V

Reviewed-by: Mikko Perttunen <mperttunen@...dia.com>

On 20.07.2018 15:45, Aapo Vienamo wrote:
> Set regulator-min-microvolt property of ldo2 to 1.8 V in
> tegra210-p2180.dtsi. ldo2 is used by the sdmmc1 SDHCI controller and its
> voltage needs to be adjusted down to 1.8 V to support faster signaling
> modes. It appears that the comment about the SDHCI driver requesting
> invalid voltages no longer applies.
> 
> Signed-off-by: Aapo Vienamo <avienamo@...dia.com>
> ---
>   arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi | 11 +----------
>   1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi b/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
> index 212e663..8496101 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
> @@ -178,16 +178,7 @@
>   
>   				vddio_sdmmc: ldo2 {
>   					regulator-name = "VDDIO_SDMMC";
> -					/*
> -					 * Technically this supply should have
> -					 * a supported range from 1.8 - 3.3 V.
> -					 * However, that would cause the SDHCI
> -					 * driver to request 2.7 V upon access
> -					 * and that in turn will cause traffic
> -					 * to be broken. Leave it at 3.3 V for
> -					 * now.
> -					 */
> -					regulator-min-microvolt = <3300000>;
> +					regulator-min-microvolt = <1800000>;
>   					regulator-max-microvolt = <3300000>;
>   					regulator-always-on;
>   					regulator-boot-on;
>