Buildroot for the CM3 IO board released

A buildroot image can now be produced for the CM3 io board.

Full details and updates available here :

At the time of writing the radxa uboot system doesn’t load boot.scr uboot scripts and execute them. This is handled by this issue Autorun a uboot script

Once build, during boot you will need to manually copy and paste boot commands into the console, check the readme for more information.

I’ve added a new branch to test audio throught he i2s1 bus on the Radxa CM3 IO board.

Clone the repo and checkout the i2s1-dummy-soundcard-cm3-io branch :

To use it, you will need to modprobe the bare codec first :

modprobe snd-soc-bare-codec.ko

As I mentioned in the commit, it outputs I2S audio data, but it seems that the latest rockchip i2s tdm driver should be patched in the linux kernel at build time. To do this I would use quilt like so :

  • in the output/buiild/linux-… directory, quilt init
  • quilt new 0001-update-rockchip-i2s-tdm-driver.patch
  • quilt add sound/soc/rockchip/rockchip_i2s_tdm.c
  • copy over the new driver to overwrite rockchip_i2s_tdm.c
  • build/test/edit as required
  • quilt refresh
  • copy over the 0001-update-rockchip-i2s-tdm-driver.patch patch in the patches directory to the patches.cm3/linux directory in the buildroot.rockchip directory
  • remove linux from output/build
  • make

You should have the latest rockchip i2s tdm driver built into the kernel as part of the buildroot build with the correct patch setup.