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After modifying a DTS file, rebuild the affected DTBs, deploy them to the target device, and confirm the correct device tree was loaded at boot.

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Build DTBs with Yocto

DTBs are built automatically as part of a full Yocto image build. To rebuild only the device trees after a DTS change without a full image rebuild:
  1. Enter a kas shell:
kas shell meta-qcom/ci/<SoC>-<board>.yml:meta-qcom/ci/qcom-distro.yml
  1. Force the kernel recipe to recompile (picks up DTS changes):
bitbake -c compile -f linux-qcom
  1. Rebuild the device image to repackage the updated DTBs into dtb.bin:
bitbake qcom-multimedia-image
Output DTB files are placed under tmp/deploy/images/<machine>/dtbs/.

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Deploy DTBs to the device

After a full Yocto build, flash the complete image to update all partitions including the DTB partition: 
cd build/tmp/deploy/images/<Machine>/<Image>-*.rootfs.qcomflash/
fastboot flash dtb_a dtb.bin
fastboot reboot

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Build DTBs standalone (without Yocto)

When using the kmake standalone workflow, build only the device trees with: 
kmake O=../kobj ARCH=arm64 dtbs
The resulting .dtb and .dtbo files are placed in ../kobj/arch/arm64/boot/dts/qcom/.

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Package multiple dtbs as FIT image

To package them into a flashable dtb.bin FIT image, use make_fitimage.sh from the qcom-dtb-metadata repository (requires the kmake-image Docker toolchain): 
kmake-image-run make_fitimage.sh \
    --metadata artifacts/qcom-dtb-metadata/qcom-metadata.dts \
    --its artifacts/qcom-dtb-metadata/qcom-next-fitimage.its \
    --kobj kobj \
    --output images

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Package dtb as single default image

To include your dtb as single and default device tree blob to be picked by uefi during boot, use generate_boot_bins.sh to package dtb.bin, passing explicitly your dtb to it. 
kmake-image-run generate_boot_bins.sh dtb
  --input <path/to/your-custom-dtb> \
  --output image/
For full standalone setup instructions, see Build the kernel without Yocto. For kmake-image utilities refer its project readme.

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Deploy DTBs to the device

After generating dtb.bin with make_fitimage.sh that packages multiple dtbs or generate_boot_bins.sh that packages single dtb: 
fastboot flash dtb_a images/dtb.bin
fastboot reboot
Flash both efi.bin and dtb.bin together after a kernel or DTS change to keep the kernel and device tree in sync. See Install & boot the kernel for the full incremental flash sequence.

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Validate DTB selection at boot

After the device reboots, confirm the expected device tree was loaded. Check the loaded compatible string: 
cat /proc/device-tree/compatible
The output should match the compatible string of your board DTS. For example, for a QCS6490 RB3 Gen 2: 
qcom,qcs6490-rb3gen2
qcom,qcs6490
Inspect the full device tree at runtime: 
dtc -I fs /proc/device-tree 2>/dev/null | head -30
Check the board model from dmesg: 
dmesg | grep -i model
If the wrong DTB was selected or the device fails to boot, see Common DT issues & fixes.