[Bug 269104] The uarts2 - uarts5 do not function on raspberry pi 4B

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 22 Jan 2023 21:36:36 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=269104

            Bug ID: 269104
           Summary: The uarts2 - uarts5 do not function on raspberry pi 4B
           Product: Base System
           Version: 13.1-RELEASE
          Hardware: arm64
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: arm
          Assignee: freebsd-arm@FreeBSD.org
          Reporter: jjrushford@gmail.com

I’ve tried using the additional serial ports that are available with a
raspberry pi 4B by enabling them in config.txt and when I try to read data on
them, I see nothing.  

Specifically, I’ve wired an Adafruit ultimate GPS to uart3, gpio pins 4 and 5.
I’ve built the RPI-firmware port and copied the uart0-5 dtb’s  to
/boot/msdos/overlays.  I then enable uart3 in /boot/msdos/config.txt with
dtoverlay=uart3 and reboot. After boot, I see that FreeBSD has created
/dev/ttyu1 and /dev/cuau1 in the dev tree for uart3.  When I try reading from
ttyu1 or cuau1, I do not see any data whatsoever.  I’ve set the baud rate to
9600 and disabled flow control but still no data is seen.  If I change the
wiring to use ttyu0, gpio pins 14 and 15, I do see data there.

Just to verify the hardware, I installed a different SD card with raspberry pi
OS, Debian, and enabled uart3 in config.txt.  When I read the /dev/ttyAMA1 I do
see the NMEA time stamps coming in uart3 at 9600 baud with no issue.  Next I
reboot back to FreeBSD 13.1, I cannot see any data from The GPS card on ttyu1
or cuau1.

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