linux-kernel - Re: [PATCH] MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts

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Date:   Fri, 23 Jun 2023 15:09:38 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        list@...ndingux.net, "H . Nikolaus Schaller" <hns@...delico.com>
Subject: Re: [PATCH] MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts

On Thu, Jun 22, 2023 at 07:59:34PM +0200, Paul Cercueil wrote:
> Commit 08384e80a70f ("MIPS: DTS: CI20: Fix ACT8600 regulator node
> names") caused the VDDCORE power supply (regulated by the ACT8600's
> DCDC1 output) to drop from a voltage of 1.2V configured by the
> bootloader, to the 1.1V set in the Device Tree.
> 
> According to the documentation, the VDDCORE supply should be between
> 0.99V and 1.21V; both values are therefore within the supported range.
> 
> However, VDDCORE being 1.1V results in the CI20 being very unstable,
> with corrupted memory, failures to boot, or reboots at random. The
> reason might be succint drops of the voltage below the minimum required.
> 
> Raising the minimum voltage to 1.125 volts seems to be enough to address
> this issue, while still keeping a relatively low core voltage which
> helps for power consumption and thermals.
> 
> Fixes: 08384e80a70f ("MIPS: DTS: CI20: Fix ACT8600 regulator node names")
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> 
> ---
> Cc: H. Nikolaus Schaller <hns@...delico.com>
> ---
>  arch/mips/boot/dts/ingenic/ci20.dts | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/boot/dts/ingenic/ci20.dts b/arch/mips/boot/dts/ingenic/ci20.dts
> index cec0caa2350c..a141a699b790 100644
> --- a/arch/mips/boot/dts/ingenic/ci20.dts
> +++ b/arch/mips/boot/dts/ingenic/ci20.dts
> @@ -298,8 +298,8 @@ act8600: act8600@5a {
>  
>  		regulators {
>  			vddcore: DCDC1 {
> -				regulator-min-microvolt = <1100000>;
> -				regulator-max-microvolt = <1100000>;
> +				regulator-min-microvolt = <1125000>;
> +				regulator-max-microvolt = <1125000>;
>  				vp1-supply = <&vcc_33v>;
>  				regulator-always-on;
>  			};
> -- 
> 2.40.1

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]