Hi Philip,
If you convert the dtb file to dts, you will see
dtc -I dtb -O dts tegra186-a02-bpmp-storm-p3489-a00-00-ta795sa-ucm1.dtb > /tmp/storm.dts
that the select node is actually containing a phandle of external-memory-X. Each of these external-memory-X is a configuration for a make of DDR, may be Samsung, hynix etc. If you feed 0x8 to all the 4 entries, then irrespective of the strap value from the pins, only 0x8 settings will be applied
emc-strap {
select = <0x8 0x9 0x0 0x0>;
};
external-memory-0 {
compatible = "nvidia,tegra18-emc";
reg = <0x0 0x2c10000 0x0 0x10000>;
#address-cells = <0x1>;
#size-cells = <0x0>;
linux,phandle = <0x8>;
<b>phandle = <0x8>;</b>
regards
Bibek