Why Device Tree Structure (DTS) file is needed both in bootloader and kernel source code?
Bootloaders like U-Boot that do not implement the Open Firmware API, are expected to pass to the kernel a binary form of the flattened device tree - LinuxFDTBlob
Why are the DTS files present in the kernel as well? Isn't that redundant?
As an example, U-boot source code has following file:
arch/arm/dts/tegra124-jetson-tk1.dts
This file can also be found under Linux source code:
arch/arm/boot/dts/tegra124-jetson-tk1.dts
Although the kernel version is 4 times the U-boot version, I would like to know the reason behind this redundancy. I believe it is harder to maintain and use both for the maintainers and the developers
Answer
Below is the answer from the comments of Artlessnoise:
The u-boot source uses the u-boot DTB while Linux uses Linux DTB when kernel boots. The u-boot version is a stripped down version as there are not as many peripherals needed to boot. You always use the kernel version for Linux i.e. u-boot passes this one to Linux (as well as load bzImage or vmlinux).
Many of the u-boot drivers are almost identical to Linux. Obviously, you can make the same argument for all the u-boot drivers; most are copies of the Linux drivers with interrupts replaced by polling routines. Using the same open-firmware interface enables them to match closer.