U-boot.cfg

[Raelene Heersink]

Iam 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.

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.

Also I added some debug statements in the serial-uclass.c. In serial_find_console_or_panic(), I am falling into the following conditional (below). Hitting this conditional seems to indicate that I am not finding UART4 in the FDT (flattened device tree). Do I need to rebuild the device tree binary so it has UART4 available. My understanding however was that this is more of a Linux kernel type thing, and wouldn't be relevant to configuring the board until the kernel is loaded?

Maxwell Bezold said:Do I need to rebuild the device tree binary so it has UART4 available. My understanding however was that this is more of a Linux kernel type thing, and wouldn't be relevant to configuring the board until the kernel is loaded?

No this is not needed for u-boot stage. DTS is loaded by u-boot, but it is used by the kernel to further configure your device. So in order to configure UAR4 in u-boot you DO NOT need DTS. Try adding

I am using U-Boot v2018.01 and patching mux_data.h with data generated from TI's PinMux Tool. CONFIG_TI_QSPI is enabled in u-boot.cfg. I hoped that would be enough to detect the flash but when I "sf probe" from U-Boot I get nothing except "(err=-19)". The QSPI flash is a Micron MT25QL256ABA.

I will give that a go when I have some time. I was able to get Linux to probe the QSPI flash and format it so at leat the hardware appears to be working. We'll see what happens with U-Boot. Thank you, Marcus.

3a8082e126