Someone created a thread on the U-Boot mailing list [1], referencing work
done to support variants of RK3399 SoCs with different types of DRAM [2].
This patch configures the Nano Pi R4S to use DDR3 instead of LPDDR4, but
will be removed once [2] is included in a future U-Boot release.  This
patch was created around April 2023 by Herman Rimm <herman@rimm.ee> for
personal use and has only been submitted to GNU Guix.

[1]: https://patchwork.ozlabs.org/project/uboot/patch/WwCslkoi6ts6A8RCd6KlxuRAMpItkfneEG-3BbNbG61gWVz0A2A3-0hl_Jg7W9quLr19luuiiT7naEi7djncCaEruUOnVq3pnb9dQFU_GqY=@protonmail.com/#2973664
[2]: https://github.com/anaelorlinski/OpenWrt-NanoPi-R2S-R4S-Builds/commit/9d836044340ddef53f5d9f1946ac48c946a78284

diff --git a/arch/arm/dts/rk3399-nanopi-r4s-u-boot.dtsi b/arch/arm/dts/rk3399-nanopi-r4s-u-boot.dtsi
index 69800cc368..a3054849f8 100644
--- a/arch/arm/dts/rk3399-nanopi-r4s-u-boot.dtsi
+++ b/arch/arm/dts/rk3399-nanopi-r4s-u-boot.dtsi
@@ -13,7 +13,7 @@
  */
 
 #include "rk3399-nanopi4-u-boot.dtsi"
-#include "rk3399-sdram-lpddr4-100.dtsi"
+#include "rk3399-sdram-ddr3-1866.dtsi"
 
 / {
 	smbios {
diff --git a/configs/nanopi-r4s-rk3399_defconfig b/configs/nanopi-r4s-rk3399_defconfig
index 4f4363cb0f..bfa7ee628d 100644
--- a/configs/nanopi-r4s-rk3399_defconfig
+++ b/configs/nanopi-r4s-rk3399_defconfig
@@ -54,7 +54,6 @@ CONFIG_PMIC_RK8XX=y
 CONFIG_REGULATOR_PWM=y
 CONFIG_REGULATOR_RK8XX=y
 CONFIG_PWM_ROCKCHIP=y
-CONFIG_RAM_ROCKCHIP_LPDDR4=y
 CONFIG_BAUDRATE=1500000
 CONFIG_DEBUG_UART_SHIFT=2
 CONFIG_SYS_NS16550_MEM32=y