[U-Boot] Raspberry PI Compute Module - UART Issue

[Lee Annamalai]

Hi

I am using a Raspberry PI compute module (CM 3+), which seems to be running U-Boot - U-Boot 2019.04-dirty (Aug 21 2019 - 14:41:54 +0000)

The CM3+ is communicating on the UART at boot, before the Kernel loads:

U-Boot 2019.04-dirty (Aug 21 2019 - 14:41:54 +0000)

DRAM:  948 MiB
RPI Compute Module 3 (0xa220a0)
MMC:   mmc at 7e202000: 0, sdhci at 7e300000: 1
Loading Environment from FAT... WARNING at drivers/mmc/bcm2835_sdhost.c:408/bcm2835_send_command()!
WARNING at drivers/mmc/bcm2835_sdhost.c:408/bcm2835_send_OK
In:    serial
Out:   serial
 1  0
WARNING at drivers/mmc/bcm2835_sdhost.c:408/bcm2835_send_command()!
WARNING at drivers/mmc/bcm2835_sdhost.c:408/bcm2835_send_command()!
switch to partitions #0, OK
mmc0(part 0) is current device
LOADBOOTENV
Running uenvcmd ...
ENVCMD
6697472 bytes read in 285 ms (22.4 MiB/s)
3647066 bytes read in 155 ms (22.4 MiB/s)
42064 bytes read in 12 ms (3.3 MiB/s)
Kernel image @ 0x200000 [ 0x000000 - 0x663200 ]
## Flattened Device Tree blob at 02000000
   Booting using the fdt blob at OK
   Loa
Starting kern



I however have a serial device connected to the UART and it starts communicating on power on to the UART. This is causing the boot process to stop.

I would like to find out how to stop U-BOOT from reading messages on the UART at boot?

Regards
Lee Annamalai