Hello there,
I am using Yocto to build the image for the BBB with the use of meta-ti layer. The generated image is a bit different from the generic one I am used to, i.e., it has no uEnv.txt and I figured I could load the custom device tree overlay via the extlinux/extlinux.conf file. Right now it looks like that:
root@beaglebone:~# cat /boot/extlinux/extlinux.conf
# Generic Distro Configuration file generated by OpenEmbedded
LABEL Poky (Yocto Project Reference Distro)
KERNEL ../zImage
FDTDIR ../
FDTOVERLAYS ../beaglenode.dtbo
APPEND root=PARTUUID=${uuid} rootwait rw console=${console},${baudrate}
And the boot dir:
root@beaglebone:/boot# ls -l
-rwxr-xr-x 1 root root 110068 Apr 5 2011 MLO
-rwxr-xr-x 1 root root 89315 Apr 5 2011 am335x-bone.dtb
-rwxr-xr-x 1 root root 93883 Apr 5 2011 am335x-boneblack-wireless.dtb
-rwxr-xr-x 1 root root 93434 Apr 5 2011 am335x-boneblack.dtb
-rwxr-xr-x 1 root root 90586 Apr 5 2011 am335x-boneblue.dtb
-rwxr-xr-x 1 root root 91607 Apr 5 2011 am335x-bonegreen-wireless.dtb
-rwxr-xr-x 1 root root 89642 Apr 5 2011 am335x-bonegreen.dtb
-rwxr-xr-x 1 root root 298 Mar 11 19:59 beaglenode.dtbo
drwxr-xr-x 2 root root 4096 Apr 5 2011 extlinux
-rwxr-xr-x 1 root root 898796 Apr 5 2011 u-boot.img
-rwxr-xr-x 1 root root 5214720 Apr 5 2011 zImage
The /beaglenode.dtbo is my custom device tree overlay blob, which I for now manually compiled and placed there. It looks like this so far:
/dts-v1/;
/plugin/;
/ {
compatible = "ti,am335x-bone-black", "ti,am335x-bone", "ti,am33xx";
fragment@0 {
target = <&lcdc>;
__overlay__ {
status = "disabled";
};
};
};
What I am trying to accomplish, is to disable all GPIO pins used for the lcd/ hdmi control. With the help of the above overlay, I was able to:
- Stop seeing the output on the connected via HDMI screen,
- Stop seeing the
[ 3.056701] tilcdc 4830e000.lcdc: bound 0-0070 (ops tda998x_ops)ebtry during boot.
What I would still like to do is to manually make sure that the GPIOs (i.e., the whole nxp_hdmi_bonelt_pins) are unused/ uninitialized. My problem is that:
- I donāt know (during OS runtime) how to check in what mode which pin is,
- I donāt know how to deinitialize them in the overlay.
For the latter, I tried this in the overlay:
target = <&nxp_hdmi_bonelt_pins>;
__overlay__ {
status = "disabled";
};
With probably no effect. During runtime I am looking in the /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single directory to check how different files look like, but it seems that no matter what I change in the overlay, these are fixedā¦
How to check each pin current mode?
How to deninitialize (high Z) all HDMI GPIOs?
I would appreciate all feedback!
. This is the HW I am doing this for: