linux-kernel - Re:Re: [PATCH] arm64: dts: allwinner: h6: Enable CPU opp tables for OrangePi One Plus

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Date:   Sun, 8 May 2022 21:29:01 +0800 (GMT+08:00)
From:   Chukun Pan <amadeus@....edu.cn>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Maxime Ripard <maxime@...no.tech>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re:Re: [PATCH] arm64: dts: allwinner: h6: Enable CPU opp tables for OrangePi One Plus

>The AXP805 datasheet has this information in the description for REG 1A.
>DVM is disabled by default, and when it is enabled, the default ramp rate
>is 10mV/15.625 us == 640 uV/us.
>
>Did you notice any instability without this delay?

Actually I write this based on the commit https://github.com/torvalds/linux/commit/ebae33c
("arm64: dts: allwinner: h6: Enable CPU opp tables for Orange Pi 3") and https://github.com/
torvalds/linux/commit/fe79ea5 ("arm64: dts: allwinner: h6: Enable CPU opp tables for Pine
H64"), so I think it's necessary to add this delay.

>> @@ -216,6 +222,7 @@ reg_dcdcc: dcdcc {
>>  				regulator-enable-ramp-delay = <32000>;
>>  				regulator-min-microvolt = <810000>;
>>  				regulator-max-microvolt = <1080000>;
>> +				regulator-ramp-delay = <2500>;
>
>This change is not related to CPU frequency scaling, so it belongs in a separate
>patch (if it is needed).

The two commits mentioned above also add this delay to dcdcc regulator.
If there is a need for a separate patch, I will send these separately.

Thanks,
Chukun