RPi3: serial console

[Peter Robinson]

On Mon, Oct 12, 2020 at 3:56 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> Hello Matthias,
>
> I have upgraded the Raspberry 3 firmware from raspi3-firmware
> (1.20190215-1+deb10u4) to raspi-firmware (1.20200601-3)
> [https://packages.debian.org/bullseye/raspi-firmware].
>
> After the upgrade the output of U-Boot on the serial console is complete
> gibberish as if the baudrate were incorrect. The output from the Linux
> kernel is fine at 115200 baud.

I've seen similar on all firmware since around mid April up until
recently, it seems to be fixed with releases in Oct (I'm using one
from Oct 8th), I'm not sure if it can be fixed in U-Boot but it seems
to be due to a change in the firmware.

> I observe this both with rpi_3_defconfig and rpi_arm64_defconfig,
> v2020.10 and current origin/master.
>
> config.txt:
>
> arm_control=0x200
> enable_uart=1
> upstream_kernel=1
> kernel=u-boot.bin
>
> boot.scr:
> setenv autoload no
> dhcp
> load mmc 0:1 $fdt_addr_r bcm2710-rpi-3-b-plus.dtb
> load mmc 0:2 $kernel_addr_r EFI/debian/grubaa64.efi
> bootefi $kernel_addr_r $fdt_addr_r
>
> Best regards
>
> Heinrich