Hello,

I ran into an issue with the UART interface and U-Boot on a Raspberry Pi 3 (rpi_3_32b_defconfig). In my config.txt I have added the following lines:

dtparam=spi=on enable_uart=1 core_freq=250 dtoverlay=pi3-disable-bt

This works fine when directly booting the Linux kernel, however when using U-Boot as an intermediate step, I’m running into issues when accessing the UART interface.

As I’m using the Yocto meta-raspberrypi layer, Initially I opened a GitHub issue: https://github.com/agherzan/meta-raspberrypi/issues/374

I was pointed to the following lines that are used in the U-Boot device-tree for the Raspberry Pi 3: https://github.com/u-boot/u-boot/blob/master/arch/arm/dts/bcm2837-rpi-3-b.dt.... Possibly these would conflict with the “pi3-disable-bt” overlay.

After removing these lines, and making sure that the GPS module connected to the UART interface would not interrupt the boot process, all works fine. See also: https://github.com/agherzan/meta-raspberrypi/issues/374#issuecomment-4575244...

Is this a bug and should this be fixed in the U-Boot repository, or is this expected behaviour and Is patching the bcm2837-rpi-3-b.dts device-tree when using the pi3-disable-bt device-tree overlay the way to go?

Thanks!

Cheers, Orne