linux-kernel - Re: [PATCH v4 2/2] ARM: dts: sun8i-r40: add opp table for cpu

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Date:   Mon, 16 May 2022 17:07:29 +0800
From:   qianfan <qianfanguijin@....com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     linux-sunxi@...ts.linux.dev, Rob Herring <robh+dt@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v4 2/2] ARM: dts: sun8i-r40: add opp table for cpu



在 2022/5/16 16:53, Maxime Ripard 写道:
> On Mon, May 16, 2022 at 10:15:16AM +0800, qianfanguijin@....com wrote:
>> From: qianfan Zhao <qianfanguijin@....com>
>>
>> OPP table value is get from allwinner lichee linux-3.10 kernel driver
>>
>> Signed-off-by: qianfan Zhao <qianfanguijin@....com>
>> ---
>>   arch/arm/boot/dts/sun8i-r40.dtsi | 42 ++++++++++++++++++++++++++++++++
>>   1 file changed, 42 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/sun8i-r40.dtsi b/arch/arm/boot/dts/sun8i-r40.dtsi
>> index 291f4784e86c..8949153eb0eb 100644
>> --- a/arch/arm/boot/dts/sun8i-r40.dtsi
>> +++ b/arch/arm/boot/dts/sun8i-r40.dtsi
>> @@ -54,6 +54,36 @@ / {
>>   	#size-cells = <1>;
>>   	interrupt-parent = <&gic>;
>>   
>> +	cpu0_opp_table: opp_table0 {
>> +		compatible = "operating-points-v2";
>> +		opp-shared;
>> +
>> +		opp-720000000 {
>> +			opp-hz = /bits/ 64 <720000000>;
>> +			opp-microvolt = <1000000 1000000 1300000>;
>> +			clock-latency-ns = <2000000>;
>> +		};
>> +
>> +		opp-912000000 {
>> +			opp-hz = /bits/ 64 <912000000>;
>> +			opp-microvolt = <1100000 1100000 1300000>;
>> +			clock-latency-ns = <2000000>;
>> +		};
>> +
>> +		opp-1008000000 {
>> +			opp-hz = /bits/ 64 <1008000000>;
>> +			opp-microvolt = <1160000 1160000 1300000>;
>> +			clock-latency-ns = <2000000>;
>> +		};
>> +
>> +		/* The opp table of the cpu frequency that exceeds 1G
>> +		 * is not defined here. They require higher operating
>> +		 * current, which may exceed the 500mA limited if the
>> +		 * system is powered by USB. You can add them to the
>> +		 * board's DTS is you make sure.
>> +		 */
> That's not the issue though. The issue is that the board is setup with a
> CPU voltage at 1160mV, and if we raise the frequency to a higher OPP
> without raising the voltage as well, the CPU will crash.
Yes, this is a issue and if the dts doesn't has "cpu-supply" node.
The comment above is found while testing. 100% cpu load @ 4x1.2G
will consume about 800mA@5V current, the board will reboot if it
is powered by USB. So I leave those comments.

I am thinking your suggestion to write the opp part to a dtsi like
A64. Should I adding all supported freq?

I am preparing a new version which including cpu cooling.
>
> Maxime