No corresponding baud rate setting for `enable_rp1_uart`

[JinShil]

Describe the bug

The BOOT_UART configuration has a corresponding UART_BAUD setting.
The console= kernel command line argument allows for baud rate configuration.
However, the enable_rp1_uart doesn't seem to have a corresponding baud rate setting. Unless, I've overlooked it.

It's helpful to set a high baud rate for the early logging features of the bootloader and kernel as it can shave a few seconds off of the overall boot times. But, if each stage of the boot process does not have the same baud rate, you end up with output like this:

See the forum thread that prompted this issue report at https://forums.raspberrypi.com/viewtopic.php?t=391976

Steps to reproduce the behaviour

Try to set the baud rate for each stage of the boot process to something other than 115200.

Device (s)

Other

Bootloader configuration.

[all]
BOOT_UART=1
UART_BAUD=921600
BOOT_ORDER=0xf641
NET_INSTALL_AT_POWER_ON=1
BOOT_WATCHDOG_TIMEOUT=30
HDMI_DELAY=0
PSU_MAX_CURRENT=5000
USB_MSD_DISCOVER_TIMEOUT=5000

[gpio16=1]
BOOT_ORDER=0xf14

[gpio17=1]
BOOT_ORDER=0xf146
PCIE_PROBE=1

System

No response

Bootloader logs

No response

USB boot

No response

NVMe boot

No response

Network (TFTP boot)

No response

[timg236]

You can already configure the baud rate for the RP1 UART in the Linux kernel via the command line.

There's no baud rate control for RP1 UART in the bootloader, it doesn't really make sense to try and make this go fast because there is a high overhead (per byte) in talking to RP1 UART in the bootloader since the VPU can't access it directly. Therefore, for boot optimisation just turn off enable_rp1_uart=1

I'll leave it open as low priority feature request.