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

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Message-Id: <8024618C-BB30-46CD-8B2F-299C04308974@goldelico.com>
Date:   Fri, 23 Jun 2023 15:23:48 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Paul Cercueil <paul@...pouillou.net>,
        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
Subject: Re: [PATCH] MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts

Hi Thomas,
you are again too fast. Please let people enough time to test and comment patches.

I have started ca. 1 hour ago to do more tests on this topic and am currently in the middle of testing this.

At the moment it looks as if I would recommend not to apply it now. Since I have no problems with 1.10V with the letux-os distribution kernel (which adds some other patches and uses a different defconfig) but only with upstream and ci20_defconfig. So a proper solution may be completely different.

Best regards,
Nikolaus


> Am 23.06.2023 um 15:09 schrieb Thomas Bogendoerfer <tsbogend@...ha.franken.de>:
> 
> 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 ]