[PATCH v2] arm64: dts: rockchip: Add GPU OPP voltage ranges to RK356x SoC dtsi

[Dragan Simic]

Add support for voltage ranges to the GPU OPPs defined in the SoC dtsi for
RK356x.  These voltage ranges are useful for RK356x-based boards that are
designed to use the same power supply for the GPU and NPU portions of the
SoC, which is described further in the following documents:

  - Rockchip RK3566 Hardware Design Guide, version 1.1.0, page 37
  - Rockchip RK3568 Hardware Design Guide, version 1.2, page 78

The values for the exact GPU OPP voltages and the lower limits for the GPU
OPP voltage ranges differ from the values found in the vendor kernel source
(cf. downstream commit f8b9431ee38e ("arm64: dts: rockchip: rk3568: support
adjust opp-table by otp")). [1][2]  However, our values have served us well
so far, so let's keep them for now, until we actually start supporting the
CPU and GPU binning, together with the related voltage adjustments.

[1] https://github.com/rockchip-linux/kernel/commit/f8b9431ee38ed561650be7092ab93f564598daa9
[2] https://raw.githubusercontent.com/rockchip-linux/kernel/f8b9431ee38ed561650be7092ab93f564598daa9/arch/arm64/boot/dts/rockchip/rk3568.dtsi

Suggested-by: Diederik de Haas <didi.debian at cknow.org>
Helped-by: Jonas Karlman <jonas at kwiboo.se>
Signed-off-by: Dragan Simic <dsimic at manjaro.org>
---

Notes:
    Changes in v2:
      - Dropped support for optional GPU OPP voltage ranges, which may
        actually hide some misconfiguration issues in board dts files, [3]
        but that will be covered by other debugging patches [4]
    
    Link to v1: https://lore.kernel.org/linux-rockchip/446399362bd2dbeeaecd8351f68811165429749a.1719637113.git.dsimic@manjaro.org/T/#u
    
    [3] https://lore.kernel.org/linux-rockchip/f10d5a3c425c2c4312512c20bd35073c@manjaro.org/
    [4] https://lore.kernel.org/linux-rockchip/36170f8485293b336106e92346478daa@manjaro.org/

 arch/arm64/boot/dts/rockchip/rk356x.dtsi | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk356x.dtsi b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
index d8543b5557ee..ec772bce359a 100644
--- a/arch/arm64/boot/dts/rockchip/rk356x.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
@@ -195,32 +195,32 @@ gpu_opp_table: opp-table-1 {
 
 		opp-200000000 {
 			opp-hz = /bits/ 64 <200000000>;
-			opp-microvolt = <825000>;
+			opp-microvolt = <825000 825000 1000000>;
 		};
 
 		opp-300000000 {
 			opp-hz = /bits/ 64 <300000000>;
-			opp-microvolt = <825000>;
+			opp-microvolt = <825000 825000 1000000>;
 		};
 
 		opp-400000000 {
 			opp-hz = /bits/ 64 <400000000>;
-			opp-microvolt = <825000>;
+			opp-microvolt = <825000 825000 1000000>;
 		};
 
 		opp-600000000 {
 			opp-hz = /bits/ 64 <600000000>;
-			opp-microvolt = <825000>;
+			opp-microvolt = <825000 825000 1000000>;
 		};
 
 		opp-700000000 {
 			opp-hz = /bits/ 64 <700000000>;
-			opp-microvolt = <900000>;
+			opp-microvolt = <900000 900000 1000000>;
 		};
 
 		opp-800000000 {
 			opp-hz = /bits/ 64 <800000000>;
-			opp-microvolt = <1000000>;
+			opp-microvolt = <1000000 1000000 1000000>;
 		};
 	};