Re: [PATCH 1/2] arm64: dts: rk3328: add gpu opp table

[Nicolas Frattaroli <frattaroli.nicolas@gmail.com>]

On Samstag, 16. Oktober 2021 17:45:44 CEST Trevor Woerner wrote:
> Add an operating-points table and cooling entry to the GPU on the
> RK3328 SoC to improve its performance. According to its datasheet[1]
> the maximum frequency of the Mali-450 MP2 GPU found on the RK3328 SoC
> is 500MHz.
> 
> On my rock64 device, under x11, glmark2-es2 performance increased from
> around 60 to just over 100. Same device running glmark2-es2 under
> wayland/weston improved from just over 100 to just over 200.
> 
> [1] https://rockchip.fr/RK3328%20datasheet%20V1.2.pdf
> 
> Signed-off-by: Trevor Woerner <twoerner@gmail.com>
> ---
>  arch/arm64/boot/dts/rockchip/rk3328.dtsi | 26 +++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
> b/arch/arm64/boot/dts/rockchip/rk3328.dtsi index 8c821acb21ff..5e1dcf71e414
> 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
> @@ -532,7 +532,8 @@ map0 {
>  					cooling-device = <&cpu0 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
>  							 <&cpu1 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
>  							 <&cpu2 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> -							 <&cpu3 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> +							 <&cpu3 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> +							 <&gpu 
THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
>  					contribution = <4096>;
>  				};
>  			};
> @@ -617,6 +618,29 @@ gpu: gpu@ff300000 {
>  		clocks = <&cru ACLK_GPU>, <&cru ACLK_GPU>;
>  		clock-names = "bus", "core";
>  		resets = <&cru SRST_GPU_A>;
> +		operating-points-v2 = <&gpu_opp_table>;
> +		#cooling-cells = <2>;
> +	};
> +
> +	gpu_opp_table: gpu-opp-table {
> +		compatible = "operating-points-v2";
> +
> +		opp-200000000 {
> +			opp-hz = /bits/ 64 <200000000>;
> +			opp-microvolt = <1100000>;
> +		};
> +		opp-300000000 {
> +			opp-hz = /bits/ 64 <300000000>;
> +			opp-microvolt = <1100000>;
> +		};
> +		opp-400000000 {
> +			opp-hz = /bits/ 64 <400000000>;
> +			opp-microvolt = <1100000>;
> +		};
> +		opp-500000000 {
> +			opp-hz = /bits/ 64 <500000000>;
> +			opp-microvolt = <1100000>;
> +		};
>  	};
> 
>  	h265e_mmu: iommu@ff330200 {

As for whether this works as described on a ROCK64 for glmark2-es2-wayland:

Tested-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>

There is some stuff worth noting that LibreELEC does on this SoC[1]:

1. they use 1.05V for all OPPs up to and including 400 MHz
2. they run 500 MHz at 1.15V instead (though 1.10V seemed to work for both of 
us)
3. they disable 500 MHz because 1.15V was apparently too high for rkvdec.

3 is currently not very relevant because mainline Linux has no rkvdec node in 
the rk3328 dtsi, and we're not running at 1.15V.

I've decided to add their rkvdec dtsi patch[2] on top anyway, and saw no 
complaints from the rkvdec module while glmark2-es2-drm was running. However, 
it's not like I tried to actually hardware decode video while it was running 
because the userspace situation still won't let me without compiling entirely 
too much stuff from git. Though the rkvdec module was loaded and present.

[1]: https://github.com/LibreELEC/LibreELEC.tv/commit/
9a6be0d36ba7ff3c3d5df798682d47a1de594ac0
[2]: https://github.com/LibreELEC/LibreELEC.tv/blob/master/projects/Rockchip/
patches/linux/default/linux-1001-v4l2-rockchip.patch#L860-L935