Devicetree files aren’t updating in yocto image

[moose]

Hello, when I make changes to my evk board dts file, the changes don’t seem to make it to the image. To generate the image, I follow the standard procedure listed in IMXLXYOCTOUG and here is how I make the changes to my dts file:

bitbake virtual/kernel

bitbake -c devshell virtual/kernel

This opens a new shell. I make changes to imx8mn_evk.dts within tmp/work-shared/… directory and I then compile dts files within the new shell.

make dtbs

I exit the shell and then issue:

bitbake -c deploy virtual/kernel

Is this the correct procedure to update the board dts file? I am not sure if I am updating the correct file location or if I need to copy the file? Any guidance on how I should do this and why isn’t it working that would be appreciated. Thank you!

[amberworth]

I've been using devtool to make changes to the device trees.

[moose]

@amberworth any chance you could provide more details or instructions? I have used devtool to create/modify/upgrade a recipe but not sure how to use it to modify and update a devicetree file. Thank you!

[amberworth · Accepted solution]

Sure.  Say I wanted to modify the devtree for an imx8m nano (ddr4 version):

I source my setup script into the build directory then:

1. devtool modify linux-imx  - This pulls and patches sources (including device tree entries)
2. modify the device tree that has been pulled and patched into the workspace ( <build dir>/workspace/workspace/sources/linux-imx/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts)
3. devtool build-image <image name> 
4. load on to board with new image with uuu
5. devtool finish (or update) to create patches and push changes from the workspace to your layer

[moose]

Thank you @amberworth for the detailed instructions. This actually worked just fine. I was also able to get it working using the devshell method. I found this link to be useful https://stackoverflow.com/questions/34175786/how-to-install-kernel-patch-locally-in-yocto/34187967

Thanks!