gpiochip order unexpected, device tree gpio0 becomes /dev/gpiochip3

gpiochip order unexpected, device tree gpio0 becomes /dev/gpiochip3

[Katu Txakur]

Hi,

I've built a, Yocto scarthgap, core-image-minimal for the machine=beaglebone. When I booted what it's defined as gpio0 in the device tree, it becomes /dev/gpiochip3. The rest are in order. 
This also happened using the beaglebone-yocto machine.
This also happened using the beaglebone-yocto machine in Yocto kirkstone branch.

Below the core-image-minimal.yaml file that I used to create the image.
I had to manually edit /boot/extlinux/extlinux.conf and delete the root password manually, but I'm not asking about that.

Also the meta-arm doesn't seem to have a scarthgap branch, I used master.

Thank you,
Katu

header:
  version: 1

distro: poky
machine: beaglebone

repos:
  poky:
    url: http://git.yoctoproject.org/poky
    branch: scarthgap
    layers:
      meta:
      meta-poky:
      meta-yocto-bsp:
  meta-arm:
    url: https://git.yoctoproject.org/meta-arm
    branch: master
    layers:
      meta-arm:
      meta-arm-bsp:
      meta-arm-systemready:
      meta-arm-toolchain:
  meta-ti:
    url: https://git.yoctoproject.org/meta-ti
    branch: scarthgap
    commit: 5c049dcb30d7a644333762198771d7fd3795b686
    layers:
      meta-ti-bsp:
      meta-ti-extras:
  meta-openembedded:
    url: https://github.com/openembedded/meta-openembedded.git
    branch: scarthgap
    commit: 1731d7ca9c75039040f8ce98009c2761707a9671
    layers:
      meta-oe:
      meta-networking:
      meta-python:

local_conf_header:
  base: |
    CONF_VERSION = "2"
    INIT_MANAGER = "systemd"

target:
  - core-image-minimal
local_conf_header:
    custom-local-conf: |
        ACCEPT_FSL_EULA = "1"
        # Switch to Debian packaging and include package-management in the image
        PACKAGE_CLASSES = "package_deb"
        EXTRA_IMAGE_FEATURES += "package-management"
        LICENSE_FLAGS_ACCEPTED = "commercial"
    standard: |
        CONF_VERSION = "2"
    folders: |
        BB_GENERATE_MIRROR_TARBALLS = "1"
        DEPLOY_DIR = "${TOPDIR}/deploy"
        SSTATE_DIR = "${TOPDIR}/sstate-cache"
    rmwork: |
        INHERIT += "rm_work"
    other: |
        EXTRA_IMAGE_FEATURES ?= "debug-tweaks"

Re: [meta-ti] gpiochip order unexpected, device tree gpio0 becomes /dev/gpiochip3

[Denys Dmytriyenko]

On Wed, Apr 17, 2024 at 06:39:02AM -0700, Katu Txakur wrote:
> Hi,
> 
> I've built a, Yocto scarthgap, core-image-minimal for the 
> machine=beaglebone. When I booted what it's defined as gpio0 in the device 
> tree, it becomes /dev/gpiochip3. The rest are in order.
> This also happened using the beaglebone-yocto machine.
> This also happened using the beaglebone-yocto machine in Yocto kirkstone 
> branch.

man udev

| udev supplies the system software with device events, manages permissions 
| of device nodes and may create additional symlinks in the /dev/ directory, 
| or renames network interfaces. The kernel usually just assigns unpredictable 
| device names based on the order of discovery. Meaningful symlinks or network 
| device names provide a way to reliably identify devices based on their 
| properties or current configuration. 

You can check which bus, device or address a specific dev node corresponds to:

udevadm info /dev/gpiochip3

More details are in the corresponding entries of the virtual /sys filesystem.

-- 
Denys