On 2020-10-16 03:28, Ricardo Salveti wrote: > On Tue, Oct 13, 2020 at 11:04 AM Peter Robinson <pbrobin...@gmail.com> 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. >> > >> > Thanks for confirming the problem. >> >> For reference I have found a number of other problems with recent >> firmwares and 2020.10 release: >> * U-Boot crashes on a RPi4 8Gb model if you don't have a display connected >> [1] >> * It doesn't boot, not sure if it's a crash or something else, you >> just get the rainbow screen, if you don't have the uart enabled in >> config.txt (ie just using a display for output). > > Noticed the same as well here (boots fine only with enable_uart=1). > While playing over with the files I noticed it works fine with the > latest firmware when using an older bcm2710-rpi-3-b-plus.dtb > (placed together with the firmware). If I use the latest > bcm2710-rpi-3-b-plus.dtb from the 5.4 downstream kernel, it doesn't > work (only tested on rpi3-b-plus). > > This is with CONFIG_OF_BOARD=y, if I use CONFIG_OF_EMBED instead it > works just fine (which gives me the impression that u-boot might not > be happy with the dtb generated by the firmware when enable_uart is > not set).
What we noticed is adding brcm,bcm2835-pl011 compatible to the UARTs makes U-Boot 2020.10 boot even *without* enable_uart=1. dm shows that with this change CONFIG_BCM283X_PL011_SERIAL is in use... >From what I understand, this driver checks if the UART is muxed, and if not bails out. So I guess without that compatible string, when the regular PL011 driver is used, it seems that U-Boot tries to initialize UART and fails? -- Stefan