I am happy to confirm that the build as suggested by @simonsouth works and gets me to the uboot console. I tried with both u-boot 2019.10 and the suggested patches as well as with current master (2020.04-rc3 + later commits) without patches.
Unfortunately, it does not work when flashed to SPI instead of when booting from sdcard. In this case it hangs bails out after not recognizing neither mmc1 nor mmc2 (though it recognizes mmc2 when I put in the eMMC flash memory)
@ayufan since you managed to produce images that boot from SPI as well: Is this a matter of configuraton/build parameters or does this require extra-patches?
Unfortunately, it does not work when flashed to SPI instead of when booting from sdcard. In this case it hangs bails out after not recognizing neither mmc1 nor mmc2 (though it recognizes mmc2 when I put in the eMMC flash memory)
@ayufan since you managed to produce images that boot from SPI as well: Is this a matter of configuraton/build parameters or does this require extra-patches?