Hi all,
I am trying to switch my U-boot console to use UARTO4, rather than UARTO0, so that I can use UARTO4 to issue custom U-boot boot options. I downloaded U-boot source code from here and wrote a custom config file, and then rebuilt the project. Per this including patches.
eewiki.net/.../BeagleBone+Black
Here's my config file:
CONFIG_ARM=y
CONFIG_TARGET_AM335X_EVM=y
CONFIG_SPL=y
CONFIG_SPL_STACK_R=y
CONFIG_SPL_STACK_R_ADDR=0x82000000
CONFIG_SYS_EXTRA_OPTIONS="EMMC_BOOT, SERIAL5 = 4, CONS_INDEX = 4"
# CONFIG_CMD_IMLS is not set
# CONFIG_CMD_FLASH is not set
# CONFIG_CMD_SETEXPR is not set
CONFIG_SPI_FLASH=y
I also updated the uEnv.txt and DEFAULT_LINUX_BOOT_ENV in "/include/configs/am335x_evm.h" such that my default console is:
console=ttyO4,115200n8
Each time, I have dragged the generated MLO, u-boot.img, u-boot.cfg, u-boot.bin. When I connect to the serial port, I can see the normal Linux stuff coming from /dev/ttyo4 pins, but when I go to restart Linux, I see the system reboot messages, and then I loose the serial stream until the Kernel itself is booting up, I am not presented with the option to enter the U-boot console, and I don't see any messages about the U-boot at all. Using the same U-boot files, if I view the output from /dev/ttyo0, I see the restart messages, but I see also see message from U-Boot and I see the option to enter the U-boot console.
I found this post, which seems to address the same problem I am having. I tried implement these fixes without much luck. Doesn't seem relevant to the current release of U-boot, which doesn't have a pll.c file and a def.config file.
(http://e2e.ti.com/support/arm/sitara_arm/f/791/p/264125/923544)
So is there a solution that is similar to this, but for newer versions of U-boot that don't include def.config file and pll.c?