We have a custom AM335x board. I want to write text to the LCD screen, e.g.
echo "text" > /dev/tty0
During kernel boot-up I see the message:
Console: switching to colour frame buffer device 100x37
So presumably with a frambuffer device configured for a particular font it should be possible to display text to the LCD.
However, I don't know where my LCD text-device is mapped in the /dev folder. I have a frambuffer device at /dev/fb0, but it doesn't display text directly if I echo to it. I can just display images to it using the fbv program.
I've tried most of the nodes in /dev/, e.g. tty0-6, ttyO0-6 (0 is my serial console), vcs, vcsa...
I was told to check for an fbcon device. There's no node called fbcon, but I found it here:
bash-4.2# ls /sys/class/graphics/
fb0 fbcon
bash-4.2# ls /sys/class/graphics/fbcon
cursor_blink power rotate rotate_all subsystem uevent
I set cursor_blink to 1, to see if I'd get a cursor displayed, but there's none visible. I've built U-Boot with splash screen support and it's able to display console messages to the LCD, so I know it works and should be possible. However, I can't figure out how to do it from Linux.
I also had a look at the virtual console devices:
bash-4.2# ls /sys/class/vtconsole/vtcon0/
bind name power subsystem uevent
bash-4.2# cat /sys/class/vtconsole/vtcon0/name
(S) dummy device
bash-4.2#
bash-4.2# cat /sys/class/vtconsole/vtcon1/name
(M) frame buffer device
but that's not given me anymore clues... and I'm not sure that doing bind/unbind is going to give me somewhere to write text to.
Is there a default graphical console device that AM335x writes to?
