Hi Ed, On 25/11/2019 21:47, edrose wrote: > Hi, > > I'm working on a project that uses the Raspberry Pi Compute Module 1. Much > like the CM 3, the CM 1 has two UART interfaces - the main UART at ttyAMA0, > and a second "mini-UART" at ttyS0. The project uses the main UART since it > works better at high speeds, so the console has been bumped over to the > mini-UART. This works fine for kernel messages and as a TTY console for > logging in and interacting with the device, however I've been unable to get > u-boot to present it's console over the mini-UART. > > I've worked deep enough into this to know that u-boot doesn't use the device > tree that is set-up in config.txt, so the parameters that I've put in there > to activate and remap the mini-UART (UART1 in dts files) to pins 40/41 > doesn't apply to u-boot. I'm using the bcm2835-rpi-b dts file currently > since it's the best fit for the hardware, but it leaves the mini-UART port > disabled. I've tried playing around with the dts files to enable/remap the > mini-UART port however I've been unsuccessful. > > Can anyone give me any pointers as to how I modify the dts files to enable > and map the second UART for u-boot to be able to use it? >
Basically there are two ways. 1) as you found out U-Boot is using an embedded device tree. The device tree it uses is specified in configs/rpi_* I suppose you are using rpi_3_defconfig, so your device-tree is: bcm2837-rpi-3-b You can find the device-tree files in arch/arm/dts where you can change the files. 2) you can update the config to use CONFIG_OF_BOARD instead of CONFIG_OF_EMBED. This will take the device-tree from the file specified in config.txt (or to be correct the RPi FW will pass this device-tree to U-Boot in a register at startup). Good luck! Matthias > Kindest regards, > Ed > > > > -- > Sent from: http://u-boot.10912.n7.nabble.com/ > _______________________________________________ > U-Boot mailing list > U-Boot@lists.denx.de > https://lists.denx.de/listinfo/u-boot > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
