[U-Boot] AR71xx / AR9331 UART initialization

Mike Monaghan mmonaghan at chipworks.net
Tue May 17 19:55:07 CEST 2016


Hello,

I'm looking for some help fixing a possible issue on AR9331 platforms
covered by the AR71xx target.  In uBoot we're getting nothing but framing
errors over serial.  Once Linux initializes the port. everything works
fine.  Digging in the code, I've been able to find that the Linux driver
for the UART:

- Enables the UART
- Pokes a Startup code to a register
- Sets Bit rate
- Set Parity, length and stop bits.

All I can find in the uBoot code is it setting the bit rate.  Am I missing
where the driver is doing the things the Linux driver does?  The data sheet
seems to indicate that the UART Enable and Startup deals with pin
multiplexing, defaults, and clock selection.  I'm wondering if that's
causing our issues.  We're using 15200/n/8/1 for Linux and uBoot.  I'm
using a vendor provided version of uBoot.

Thanks,

Mike


More information about the U-Boot mailing list