[U-Boot] Beagleboard: SPL hangs on serial init

Manfred Huber
2013-03-23T10:11:17Z

Hi all,

probably I found the error. It should be a bug in the ROM code of the OMAP3.

Depending on the Booting Sequence of the OMAP3, SPL is hanging or not.
If ROM code configures UART3 before SPL starts from NAND it will lead to
a hang of the SPL. If UART3 is not configured, SPL boots correctly from
NAND.

If ROM code configures UART3 it leaves the UART in a bad state. Although
Transmitter is not empty (TEMT is not set), ROM code disables the UART.
Therefore Transmitter can never get empty.

In a normal Booting Sequence where NAND is for UART3 the bug will never
appear.

There are some solutions:

1. Configuring UART3 first and let Transmitter send until Transmitter is
empty.
2. Soft reset of Transmitter. (OMAP3 specific, NS16550 has no soft reset)
3. ...

Please tell me your assessment.

Best regards,
Manfred Huber