[Buildroot] No GPS data on ttymxc1 with busybox, but it works with systemd

[Thomas Petazzoni]

Hello,

On Mon, 20 Feb 2017 03:08:34 +0000, Brent Sink wrote:

> I have GPS device that is connected to a uart port on my processor.
> I have ttymxc0 which is the console output, and ttymxc1 which is the
> GPS interface.  I have build an image using buildroot that uses the
> busybox init system.  When I boot from this image and execute
> "cat /dev/ttymxc1", I see no output on the terminal and my gpsd
> service also sees nothing from the GPS receiver.
> 
> However, if I change my buildroot image to use the systemd init
> system, and boot from this image, everything is working.  When I
> execute "cat /dev/ttymxc1" I see output from the GPS receiver.
> 
> I'm trying to minimize the boot time so I would like use the busybox
> init system since it boots quicker.  Any thoughts why I'm not seeing
> any output on the ttymxc1 port when using the busybox init system?

Perhaps systemd is automatically initializing the serial ports to some
given speed/configuration.

Make sure you configure your serial port to the right
speed/configuration using the "stty" program.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com