[U-Boot] [RFT 8/8] arm: dts: exynos: Add ramp delay property to LDO regulators to Odroid XU3 family

[Lukasz Majewski <lukma@denx.de>]

Hi Krzysztof,

> Add startup time to LDO regulators of S2MPS11 PMIC on Odroid
> XU3/XU4/HC1 family of boards to be sure the voltage is proper before
> relying on the regulator.
> 
> The datasheet for all the S2MPS1x family is inconsistent here and does
> not specify unambiguously the value of ramp delay for LDO.  It
> mentions 30 mV/us in one timing diagram but then omits it completely
> in LDO regulator characteristics table (it is specified for bucks).
> 
> However the vendor kernels for Galaxy S5 and Odroid XU3 use values of
> 12 mV/us or 24 mV/us.
> 
> Without the ramp delay value the consumers do not wait for voltage
> settle after changing it.  Although the proper value of ramp delay for
> LDOs is unknown, it seems safer to use at least some value from
> reference kernel than to leave it unset.
> 
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

Reviewed-by: Lukasz Majewski <lukma@denx.de>

> ---
>  arch/arm/dts/exynos5422-odroidxu3.dts | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/arch/arm/dts/exynos5422-odroidxu3.dts
> b/arch/arm/dts/exynos5422-odroidxu3.dts index
> 9dfae90667cf..04ecc404f907 100644 ---
> a/arch/arm/dts/exynos5422-odroidxu3.dts +++
> b/arch/arm/dts/exynos5422-odroidxu3.dts @@ -45,6 +45,7 @@
>  					regulator-name = "vdd_ldo1";
>  					regulator-min-microvolt =
> <1000000>; regulator-max-microvolt = <1000000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -52,18 +53,21 @@
>  					regulator-name = "vddq_mmc0";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; };
>  
>  				ldo4_reg: LDO4 {
>  					regulator-name = "vdd_adc";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; };
>  
>  				ldo5_reg: LDO5 {
>  					regulator-name = "vdd_ldo5";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -71,6 +75,7 @@
>  					regulator-name = "vdd_ldo6";
>  					regulator-min-microvolt =
> <1000000>; regulator-max-microvolt = <1000000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -78,6 +83,7 @@
>  					regulator-name = "vdd_ldo7";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -85,6 +91,7 @@
>  					regulator-name = "vdd_ldo8";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -92,6 +99,7 @@
>  					regulator-name = "vdd_ldo9";
>  					regulator-min-microvolt =
> <3000000>; regulator-max-microvolt = <3000000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -99,6 +107,7 @@
>  					regulator-name = "vdd_ldo10";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -106,6 +115,7 @@
>  					regulator-name = "vdd_ldo11";
>  					regulator-min-microvolt =
> <1000000>; regulator-max-microvolt = <1000000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -113,6 +123,7 @@
>  					regulator-name = "vdd_ldo12";
>  					regulator-min-microvolt =
> <1800000>; regulator-max-microvolt = <1800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -120,12 +131,14 @@
>  					regulator-name = "vddq_mmc2";
>  					regulator-min-microvolt =
> <2800000>; regulator-max-microvolt = <2800000>;
> +					regulator-ramp-delay =
> <12000>; };
>  
>  				ldo15_reg: LDO15 {
>  					regulator-name = "vdd_ldo15";
>  					regulator-min-microvolt =
> <3300000>; regulator-max-microvolt = <3300000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -133,6 +146,7 @@
>  					regulator-name = "vdd_ldo16";
>  					regulator-min-microvolt =
> <2200000>; regulator-max-microvolt = <2200000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -140,6 +154,7 @@
>  					regulator-name = "vdd_ldo17";
>  					regulator-min-microvolt =
> <3300000>; regulator-max-microvolt = <3300000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -147,18 +162,21 @@
>  					regulator-name =
> "vdd_emmc_1V8"; regulator-min-microvolt = <1800000>;
>  					regulator-max-microvolt =
> <1800000>;
> +					regulator-ramp-delay =
> <12000>; };
>  
>  				ldo19_reg: LDO19 {
>  					regulator-name = "vdd_sd";
>  					regulator-min-microvolt =
> <2800000>; regulator-max-microvolt = <2800000>;
> +					regulator-ramp-delay =
> <12000>; };
>  
>  				ldo24_reg: LDO24 {
>  					regulator-name = "tsp_io";
>  					regulator-min-microvolt =
> <2800000>; regulator-max-microvolt = <2800000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  
> @@ -166,6 +184,7 @@
>  					regulator-name = "vdd_ldo26";
>  					regulator-min-microvolt =
> <3000000>; regulator-max-microvolt = <3000000>;
> +					regulator-ramp-delay =
> <12000>; regulator-always-on;
>  				};
>  




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
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