how to modify the dts file for jetson nano board

checking the dtb file in /boot/ on target. I find my modifications are in dtb. It’s very odd that where the kernel got the dtb file.

root@yisp-desktop:/home/yisp# cat /proc/device-tree/nvidia,dtsfilename
/dvs/git/dirty/git-master_linux/kernel/kernel-4.9/arch/arm64/boot/dts/…/…/…/…/…/…/hardware/nvidia/platform/t210/porg/kernel-dts/tegra210-p3448-0000-p3449-0000-a02.dts

root@yisp-desktop:/home/yisp# fdtget /boot/tegra210-p3448-0000-p3449-0000-a02.dtb / -l | grep spi
spi@7000d400
spi@7000d600
spi@7000d800
spi@7000da00
spi@70410000
root@yisp-desktop:/home/yisp# fdtget /boot/tegra210-p3448-0000-p3449-0000-a02.dtb /spi@7000d400 -l | grep spi
spi@0
spi@1
root@yisp-desktop:/home/yisp# fdtget /boot/tegra210-p3448-0000-p3449-0000-a02.dtb /spi@7000d400/spi@0/ compatible
mcp251x
root@yisp-desktop:/home/yisp# fdtget /boot/tegra210-p3448-0000-p3449-0000-a02.dtb /spi@7000d400/spi@1/ compatible
mcp251x

root@yisp-desktop:/home/yisp# ls /boot/dtb
ls: cannot access ‘/boot/dtb’: No such file or directory