linux-kernel - Re: [PATCH 1/3] arm64: dts: rockchip: Update CPU OPP voltages in RK356x SoC dtsi

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Message-ID: <0a1f13d06ec3668c136997e72d0aea44@manjaro.org>
Date: Sat, 12 Oct 2024 21:45:14 +0200
From: Dragan Simic <dsimic@...jaro.org>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: linux-rockchip@...ts.infradead.org, heiko@...ech.de,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org
Subject: Re: [PATCH 1/3] arm64: dts: rockchip: Update CPU OPP voltages in
 RK356x SoC dtsi

Hello Diederik,

On 2024-10-12 21:27, Diederik de Haas wrote:
> On Sat Oct 12, 2024 at 7:04 PM CEST, Dragan Simic wrote:
>> Update the lower/upper voltage limits and the exact voltages for the 
>> Rockchip
>> RK356x CPU OPPs, using the most conservative values (i.e. the highest 
>> per-OPP
>> voltages) found in the vendor kernel source. [1]
>> 
>> Using the most conservative per-OPP voltages ensures reliable CPU 
>> operation
>> regardless of the actual CPU binning, with the downside of possibly 
>> using
>> a bit more power for the CPU cores than absolutely needed.
>> 
>> Additionally, fill in the missing "clock-latency-ns" CPU OPP 
>> properties, using
>> the values found in the vendor kernel source. [1]
>> 
>> [1] 
>> https://raw.githubusercontent.com/rockchip-linux/kernel/f8b9431ee38ed561650be7092ab93f564598daa9/arch/arm64/boot/dts/rockchip/rk3568.dtsi
>> 
>> Related-to: eb665b1c06bc ("arm64: dts: rockchip: Update GPU OPP 
>> voltages in RK356x SoC dtsi")
>> Signed-off-by: Dragan Simic <dsimic@...jaro.org>
>> ---
>>  arch/arm64/boot/dts/rockchip/rk3568.dtsi |  1 +
>>  arch/arm64/boot/dts/rockchip/rk356x.dtsi | 18 ++++++++++++------
>>  2 files changed, 13 insertions(+), 6 deletions(-)
>> 
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3568.dtsi 
>> b/arch/arm64/boot/dts/rockchip/rk3568.dtsi
>> index 0946310e8c12..5c54898f6ed1 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3568.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk3568.dtsi
>> @@ -273,6 +273,7 @@ &cpu0_opp_table {
>>  	opp-1992000000 {
>>  		opp-hz = /bits/ 64 <1992000000>;
>>  		opp-microvolt = <1150000 1150000 1150000>;
>> +		clock-latency-ns = <40000>;
>>  	};
>>  };
>> 
>> diff --git a/arch/arm64/boot/dts/rockchip/rk356x.dtsi 
>> b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
>> index 0ee0ada6f0ab..534593f2ed0b 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk356x.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
>> @@ -134,39 +134,45 @@ cpu0_opp_table: opp-table-0 {
>> 
>>  		opp-408000000 {
>>  			opp-hz = /bits/ 64 <408000000>;
>> -			opp-microvolt = <900000 900000 1150000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>>  			clock-latency-ns = <40000>;
>>  		};
>> 
>>  		opp-600000000 {
>>  			opp-hz = /bits/ 64 <600000000>;
>> -			opp-microvolt = <900000 900000 1150000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>> +			clock-latency-ns = <40000>;
>>  		};
>> 
>>  		opp-816000000 {
>>  			opp-hz = /bits/ 64 <816000000>;
>> -			opp-microvolt = <900000 900000 1150000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>> +			clock-latency-ns = <40000>;
>>  			opp-suspend;
>>  		};
> 
> While it felt a bit much to send a patch just to remove the blank lines
> between the opp nodes, this sounds like an excellent opportunity to 
> make
> it consistent with the opp list in other DT files?

Actually, my plan is to work on the SoC binning, which will involve
touching nearly every OPP in the Rockchip DTs, and will add much more
data to each OPP node.  Thus, having empty lines as the separators
between the OPP nodes is something we should actually want, because
not having them will actually reduce the readability after the size
of the individual OPP nodes is increased.

That's the reason why I opted for having the separator lines in this
patch series, i.e. because having them everywhere should be the final
outcome, and because in this case they were already present where the
OPPs were moved or copied from.