[PATCH 3/3] arm64: dts: rockchip: Add new SoC dtsi for the RK3566T variant

[Dragan Simic]

Hello Diederik,

On 2024-10-12 21:42, Diederik de Haas wrote:
> On Sat Oct 12, 2024 at 7:04 PM CEST, Dragan Simic wrote:
>> Add new SoC dtsi file for the RK3566T variant of the Rockchip RK3566 
>> SoC.
>> The difference between the RK3566T variant and the "full-fat" RK3566 
>> variant
>> is in fewer supported CPU and GPU OPPs on the RK3566T, and in the 
>> absence of
>> a functional NPU, which we currently don't have to worry about.
>> 
>> Examples of the boards based on the RK3566T include the Pine64 
>> Quartz64 Zero
>> SBC, [2] the Radxa ROCK 3C and the Radxa ZERO 3E/3W SBCs.  
>> Unfortunately,
>> Radxa doesn't mention the use of RK3566T officially, but its official 
>> SBC
>> specifications do state that the maximum frequency for the Cortex-A55 
>> cores
>> on those SBCs is lower than the "full-fat" RK3566's 1.8 GHz, which 
>> makes
>> spotting the presence of the RK3566T SoC variant rather easy. 
>> [3][4][5]  An
>> additional, helpful cue is that Radxa handles the CPU and GPU OPPs for 
>> the
>> RK3566T variant separately in its downstream kernel. [6]
>> 
>> The CPU and GPU OPPs supported on the RK3566T SoC variant are taken 
>> from the
>> vendor kernel source, [1] which uses the values of the 
>> "opp-supported-hw" OPP
>> properties to determine which ones are supported on a particular SoC 
>> variant.
>> The actual values of the "opp-supported-hw" properties make it rather 
>> easy
>> to see what OPPs are supported on the RK3566T SoC variant, but that, 
>> rather
>> unfortunately, clashes with the maximum frequencies advertised 
>> officially
>> for the Cortex-A55 CPU cores on the above-mentioned SBCs. [2][3][4][5] 
>>  The
>> vendor kernel source indicates that the maximum frequency for the CPU 
>> cores
>> is 1.4 GHz, while the SBC specifications state that to be 1.6 GHz.  
>> Unless
>> that discrepancy is resolved somehow, let's take the safe approach and 
>> use
>> the lower maximum frequency for the CPU cores.
>> 
>> Update the dts files of the currently supported RK3566T-based boards 
>> to use
>> the new SoC dtsi for the RK3566T variant.  This actually takes the CPU 
>> cores
>> and the GPUs found on these boards out of their earlier overclocks, 
>> but it
>> also means that the officially advertised specifications [2][3][4][5] 
>> of the
>> highest supported frequencies for the Cortex-A55 CPU cores on these 
>> boards
>> may actually be wrong, as already explained above.
>> 
>> The correctness of the introduced changes was validated by decompiling 
>> and
>> comparing all affected board dtb files before and after these changes.
>> 
>> [1] 
>> https://raw.githubusercontent.com/rockchip-linux/kernel/f8b9431ee38ed561650be7092ab93f564598daa9/arch/arm64/boot/dts/rockchip/rk3568.dtsi
>> [2] https://wiki.pine64.org/wiki/Quartz64
>> [3] 
>> https://dl.radxa.com/rock3/docs/hw/3c/radxa_rock3c_product_brief.pdf
>> [4] 
>> https://dl.radxa.com/zero3/docs/hw/3e/radxa_zero_3e_product_brief.pdf
>> [5] 
>> https://dl.radxa.com/zero3/docs/hw/3w/radxa_zero_3w_product_brief.pdf
>> [6] 
>> https://github.com/radxa/kernel/commit/2dfd51da472e7ebb5ef0d3db78f902454af826b8
>> 
>> Cc: TL Lim <tllim at pine64.org>
>> Cc: Marek Kraus <gamiee at pine64.org>
>> Cc: Tom Cubie <tom at radxa.com>
>> Cc: FUKAUMI Naoki <naoki at radxa.com>
>> Helped-by: Nicolas Frattaroli <frattaroli.nicolas at gmail.com>
>> Helped-by: Jonas Karlman <jonas at kwiboo.se>
>> Signed-off-by: Dragan Simic <dsimic at manjaro.org>
>> ---
>>  .../dts/rockchip/rk3566-radxa-zero-3.dtsi     |  2 +-
>>  .../boot/dts/rockchip/rk3566-rock-3c.dts      |  2 +-
>>  arch/arm64/boot/dts/rockchip/rk3566t.dtsi     | 90 
>> +++++++++++++++++++
>>  3 files changed, 92 insertions(+), 2 deletions(-)
>>  create mode 100644 arch/arm64/boot/dts/rockchip/rk3566t.dtsi
>> 
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi 
>> b/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
>> index de390d92c35e..1ee5d96a46a1 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk3566-radxa-zero-3.dtsi
>> @@ -3,7 +3,7 @@
>>  #include <dt-bindings/gpio/gpio.h>
>>  #include <dt-bindings/leds/common.h>
>>  #include <dt-bindings/soc/rockchip,vop2.h>
>> -#include "rk3566.dtsi"
>> +#include "rk3566t.dtsi"
>> 
>>  / {
>>  	chosen {
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3566-rock-3c.dts 
>> b/arch/arm64/boot/dts/rockchip/rk3566-rock-3c.dts
>> index f2cc086e5001..9a8f4f774dbc 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3566-rock-3c.dts
>> +++ b/arch/arm64/boot/dts/rockchip/rk3566-rock-3c.dts
>> @@ -5,7 +5,7 @@
>>  #include <dt-bindings/leds/common.h>
>>  #include <dt-bindings/pinctrl/rockchip.h>
>>  #include <dt-bindings/soc/rockchip,vop2.h>
>> -#include "rk3566.dtsi"
>> +#include "rk3566t.dtsi"
>> 
>>  / {
>>  	model = "Radxa ROCK 3C";
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3566t.dtsi 
>> b/arch/arm64/boot/dts/rockchip/rk3566t.dtsi
>> new file mode 100644
>> index 000000000000..cd89bd3b125b
>> --- /dev/null
>> +++ b/arch/arm64/boot/dts/rockchip/rk3566t.dtsi
>> @@ -0,0 +1,90 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>> +
>> +#include "rk3566-base.dtsi"
>> +
>> +/ {
>> +	cpu0_opp_table: opp-table-0 {
>> +		compatible = "operating-points-v2";
>> +		opp-shared;
>> +
>> +		opp-408000000 {
>> +			opp-hz = /bits/ 64 <408000000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>> +			clock-latency-ns = <40000>;
>> +		};
>> +
>> +		opp-600000000 {
>> +			opp-hz = /bits/ 64 <600000000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>> +			clock-latency-ns = <40000>;
>> +		};
>> +
>> +		opp-816000000 {
>> +			opp-hz = /bits/ 64 <816000000>;
>> +			opp-microvolt = <850000 850000 1150000>;
>> +			clock-latency-ns = <40000>;
>> +			opp-suspend;
>> +		};
>> +
> 
> For consistency, no blank lines between the opp nodes would be nice ;)

I hope the way I already explained the background [*] provides
a satisfactory explanation for this choice. :)

[*] 
https://lore.kernel.org/linux-rockchip/0a1f13d06ec3668c136997e72d0aea44@manjaro.org/