Hi,
I need to modify the device tree sources in the kernel in way that the
boot process will configure the modified pins as soon as possible
BEFORE userland starts and the overlays name may be get echoed...
I searched the web for tutorials on the device tree but
the only two categories I found were:
1) How to handle device tree overlays or device tree explained
with overlays
2) Highly academic stuff which explains the history of the
device tree and the fundamental design ideas behind the
device tree concept.
The background:
At times of the boardfile and kernel 3.2. I had to deactivate
the two LEDs of AUDI cape to make it work together with the LCD7
cape (PIN 19 / PIN 20) or in other words, these two:
pin 18 (44e10848): gpio-leds-cape-audio.10 (GPIO UNCLAIMED) function pinmux_bone_audio_cape_led_pins group pinmux_bone_audio_cape_led_pins
pin 19 (44e1084c): gpio-leds-cape-audio.10 (GPIO UNCLAIMED) function pinmux_bone_audio_cape_led_pins group pinmux_bone_audio_cape_led_pins
This has to be done BEFORE the LCD7 wakes up...
I translated back the bbb dtb file to a dts file but without
a tutorial I will get lost and (more dangerous) will harm
the hardware.
Where can I find a tutorial on modifying the bbb.dtb directly
(and not generating additional overlay)?
Thank you very much in advance for any help!
Best regards,
mcc