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From: Shawn Guo <shawnguo@kernel.org>
To: Andrej Picej <andrej.picej@norik.com>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	robh+dt@kernel.org, kernel@pengutronix.de, leoyang.li@nxp.com,
	krzysztof.kozlowski@canonical.com, festevam@gmail.com,
	linux@rempel-privat.de, arnd@arndb.de, linux-imx@nxp.com,
	y.bas@phytec.de
Subject: Re: [PATCH RESEND 3/4] ARM: dts: imx6ul: phycore: Change USB LDO voltage for usb compliance
Date: Sat, 12 Feb 2022 13:46:27 +0800	[thread overview]
Message-ID: <20220212054627.GZ4909@dragon> (raw)
In-Reply-To: <20220131080526.1171072-4-andrej.picej@norik.com>

On Mon, Jan 31, 2022 at 09:05:25AM +0100, Andrej Picej wrote:
> From: Yunus Bas <y.bas@phytec.de>
> 
> According to the NXP usb compliance reference, the USB data lines for
> Full/Low speed are connected to the ARM USB LDO, which is set to
> minimum-voltage = 2.6V and maximum-voltage = 3.4 V. When the regulator
> is deactivated, the data lines are defaulty driven with 2.6V, which is
> not USB Full-Speed compliant. To be compliant, we need to activate the
> USB LDO regulator and set it to the value of 3V, which is the specified
> value in the USB specification.
> 
> Signed-off-by: Yunus Bas <y.bas@phytec.de>
> Signed-off-by: Andrej Picej <andrej.picej@norik.com>
> ---
>  arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi b/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> index 3cddc68917a0..2e03be3d43ec 100644
> --- a/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> +++ b/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> @@ -83,6 +83,11 @@ eeprom@52 {
>  	};
>  };
>  
> +&reg_3p0 {
> +	regulator-min-microvolt = <3000000>;
> +	regulator-always-on;

Rather than setting it always-on, shouldn't the consumer of the
regulator turn it on/off as needed?

Shawn

> +};
> +
>  &snvs_poweroff {
>  	status = "okay";
>  };
> -- 
> 2.25.1
> 

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WARNING: multiple messages have this Message-ID (diff)
From: Shawn Guo <shawnguo@kernel.org>
To: Andrej Picej <andrej.picej@norik.com>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	robh+dt@kernel.org, kernel@pengutronix.de, leoyang.li@nxp.com,
	krzysztof.kozlowski@canonical.com, festevam@gmail.com,
	linux@rempel-privat.de, arnd@arndb.de, linux-imx@nxp.com,
	y.bas@phytec.de
Subject: Re: [PATCH RESEND 3/4] ARM: dts: imx6ul: phycore: Change USB LDO voltage for usb compliance
Date: Sat, 12 Feb 2022 13:46:27 +0800	[thread overview]
Message-ID: <20220212054627.GZ4909@dragon> (raw)
In-Reply-To: <20220131080526.1171072-4-andrej.picej@norik.com>

On Mon, Jan 31, 2022 at 09:05:25AM +0100, Andrej Picej wrote:
> From: Yunus Bas <y.bas@phytec.de>
> 
> According to the NXP usb compliance reference, the USB data lines for
> Full/Low speed are connected to the ARM USB LDO, which is set to
> minimum-voltage = 2.6V and maximum-voltage = 3.4 V. When the regulator
> is deactivated, the data lines are defaulty driven with 2.6V, which is
> not USB Full-Speed compliant. To be compliant, we need to activate the
> USB LDO regulator and set it to the value of 3V, which is the specified
> value in the USB specification.
> 
> Signed-off-by: Yunus Bas <y.bas@phytec.de>
> Signed-off-by: Andrej Picej <andrej.picej@norik.com>
> ---
>  arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi b/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> index 3cddc68917a0..2e03be3d43ec 100644
> --- a/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> +++ b/arch/arm/boot/dts/imx6ul-phytec-phycore-som.dtsi
> @@ -83,6 +83,11 @@ eeprom@52 {
>  	};
>  };
>  
> +&reg_3p0 {
> +	regulator-min-microvolt = <3000000>;
> +	regulator-always-on;

Rather than setting it always-on, shouldn't the consumer of the
regulator turn it on/off as needed?

Shawn

> +};
> +
>  &snvs_poweroff {
>  	status = "okay";
>  };
> -- 
> 2.25.1
> 

  reply	other threads:[~2022-02-12  5:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-31  8:05 [PATCH RESEND 0/4] PHYTEC i.MX 6UL/ULL devicetree patches Andrej Picej
2022-01-31  8:05 ` Andrej Picej
2022-01-31  8:05 ` [PATCH RESEND 1/4] dt-bindings: arm: fsl: add PHYTEC phyGATE Tauri i.MX6 ULL Andrej Picej
2022-01-31  8:05   ` Andrej Picej
2022-02-11 13:26   ` Rob Herring
2022-02-11 13:26     ` Rob Herring
2022-01-31  8:05 ` [PATCH RESEND 2/4] ARM: dts: imx6ull: Add support for PHYTEC phyGATE-Tauri-S with i.MX 6ULL Andrej Picej
2022-01-31  8:05   ` Andrej Picej
2022-02-12  5:43   ` Shawn Guo
2022-02-12  5:43     ` Shawn Guo
2022-02-17  6:47     ` Andrej Picej
2022-02-17  6:47       ` Andrej Picej
2022-01-31  8:05 ` [PATCH RESEND 3/4] ARM: dts: imx6ul: phycore: Change USB LDO voltage for usb compliance Andrej Picej
2022-01-31  8:05   ` Andrej Picej
2022-02-12  5:46   ` Shawn Guo [this message]
2022-02-12  5:46     ` Shawn Guo
2022-02-18  9:16     ` Andrej Picej
2022-02-18  9:16       ` Andrej Picej
2022-01-31  8:05 ` [PATCH RESEND 4/4] ARM: dts: imx6ul: peb-av-02: move to 3 cell pwm Andrej Picej
2022-01-31  8:05   ` Andrej Picej

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