[hoki] USB Mode selection broken on both 2.0-release and 2.1-nightly

[0x53A]

I got a Skagen Falster Gen 6 (based on Fossil Gen 6) and installed Asteroid OS. First nightly, then release. On neither was I able to select SSH over USB, the watch was stuck in ADB mode.

As ADB is working, I tried to diagnose the issue with the help of AI. Following is the AI report, which sounds plausible to me:

---

Device: Fossil Gen 6 (Skagen variant), codename hoki
Affected versions:

• AsteroidOS 2.0, build 20260216211137
• AsteroidOS 2.1-nightly, build 20260227003819
  Kernel: 4.14.206

All evidence below was collected on AsteroidOS 2.0 and verified identical on 2.1-nightly.

Symptom

Selecting "SSH" in the AsteroidOS USB settings has no effect. The watch stays in ADB-only mode — no RNDIS network interface appears on the host.

Root cause

usb-moded.service fails on boot and enters a restart loop. Its ExecStartPre script (/usr/bin/init_ffs) writes to legacy sysfs nodes that don't exist on this kernel. The kernel uses configfs USB gadgets instead.

Evidence

1. usb-moded.service is failed:

# systemctl status usb-moded.service -l
x usb-moded.service - usb-moded USB gadget controller
     Loaded: loaded (/usr/lib/systemd/system/usb-moded.service; disabled; preset: disabled)
     Active: failed (Result: exit-code) since Thu 2025-05-29 16:30:42 UTC; 9 months 4 days ago
 Invocation: 092ac16214a04e3387e260aced43e77a
    Process: 779 ExecStartPre=/usr/bin/init_ffs (code=exited, status=1/FAILURE)

May 29 16:30:42 hoki systemd[1]: usb-moded.service: Scheduled restart job, restart counter is at 5.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Start request repeated too quickly.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Failed with result 'exit-code'.
May 29 16:30:42 hoki systemd[1]: Failed to start usb-moded USB gadget controller.

2. Journal shows init_ffs failing to write to missing sysfs nodes:

# journalctl -u usb-moded.service --no-pager -b -l
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Scheduled restart job, restart counter is at 3.
May 29 16:30:42 hoki systemd[1]: Starting usb-moded USB gadget controller...
May 29 16:30:42 hoki init_ffs[733]: /usr/bin/init_ffs: line 3: /sys/class/android_usb/android0/enable: Permission denied
May 29 16:30:42 hoki init_ffs[733]: /usr/bin/init_ffs: line 9: /sys/class/android_usb/android0/iSerial: Permission denied
May 29 16:30:42 hoki init_ffs[733]: /usr/bin/init_ffs: line 10: /sys/class/android_usb/android0/iManufacturer: Permission denied
May 29 16:30:42 hoki init_ffs[733]: /usr/bin/init_ffs: line 11: /sys/class/android_usb/android0/iProduct: Permission denied
May 29 16:30:42 hoki init_ffs[733]: /usr/bin/init_ffs: line 13: /sys/class/android_usb/android0/enable: Permission denied
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Control process exited, code=exited, status=1/FAILURE
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Failed with result 'exit-code'.
May 29 16:30:42 hoki systemd[1]: Failed to start usb-moded USB gadget controller.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Scheduled restart job, restart counter is at 4.
May 29 16:30:42 hoki systemd[1]: Starting usb-moded USB gadget controller...
May 29 16:30:42 hoki init_ffs[779]: /usr/bin/init_ffs: line 3: /sys/class/android_usb/android0/enable: Permission denied
May 29 16:30:42 hoki init_ffs[779]: /usr/bin/init_ffs: line 9: /sys/class/android_usb/android0/iSerial: Permission denied
May 29 16:30:42 hoki init_ffs[779]: /usr/bin/init_ffs: line 10: /sys/class/android_usb/android0/iManufacturer: Permission denied
May 29 16:30:42 hoki init_ffs[779]: /usr/bin/init_ffs: line 11: /sys/class/android_usb/android0/iProduct: Permission denied
May 29 16:30:42 hoki init_ffs[779]: /usr/bin/init_ffs: line 13: /sys/class/android_usb/android0/enable: Permission denied
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Control process exited, code=exited, status=1/FAILURE
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Failed with result 'exit-code'.
May 29 16:30:42 hoki systemd[1]: Failed to start usb-moded USB gadget controller.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Scheduled restart job, restart counter is at 5.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Start request repeated too quickly.
May 29 16:30:42 hoki systemd[1]: usb-moded.service: Failed with result 'exit-code'.
May 29 16:30:42 hoki systemd[1]: Failed to start usb-moded USB gadget controller.

3. The init_ffs script expects legacy android_usb sysfs:

# cat /usr/bin/init_ffs
#!/bin/sh

echo "0" > /sys/class/android_usb/android0/enable

manufacturer="$(cat /system/build.prop | grep -o 'ro.product.manufacturer=.*' | cut -d'=' -f 2)"
model="$(cat /system/build.prop | grep -o 'ro.product.model=.*' | cut -d'=' -f 2)"
serial="$(cat /proc/cmdline | sed 's/.*androidboot.serialno=//' | sed 's/ .*//')"

echo $serial       > /sys/class/android_usb/android0/iSerial
echo $manufacturer > /sys/class/android_usb/android0/iManufacturer
echo $model        > /sys/class/android_usb/android0/iProduct

echo "1" >  /sys/class/android_usb/android0/enable

4. The legacy sysfs node is a stub — missing enable, iSerial, etc.:

# ls /sys/devices/virtual/android_usb/android0/
power  state  subsystem  uevent

5. The kernel uses configfs USB gadgets instead:

# find /sys/kernel/config/usb_gadget/ -maxdepth 3
/sys/kernel/config/usb_gadget/
/sys/kernel/config/usb_gadget/g1
/sys/kernel/config/usb_gadget/g1/os_desc
/sys/kernel/config/usb_gadget/g1/os_desc/qw_sign
/sys/kernel/config/usb_gadget/g1/os_desc/b_vendor_code
/sys/kernel/config/usb_gadget/g1/os_desc/use
/sys/kernel/config/usb_gadget/g1/strings
/sys/kernel/config/usb_gadget/g1/strings/0x409
/sys/kernel/config/usb_gadget/g1/configs
/sys/kernel/config/usb_gadget/g1/configs/c.1
/sys/kernel/config/usb_gadget/g1/functions
/sys/kernel/config/usb_gadget/g1/functions/ffs.adb
/sys/kernel/config/usb_gadget/g1/UDC
/sys/kernel/config/usb_gadget/g1/bcdUSB
/sys/kernel/config/usb_gadget/g1/bcdDevice
/sys/kernel/config/usb_gadget/g1/idProduct
/sys/kernel/config/usb_gadget/g1/idVendor
/sys/kernel/config/usb_gadget/g1/bMaxPacketSize0
/sys/kernel/config/usb_gadget/g1/bDeviceProtocol
/sys/kernel/config/usb_gadget/g1/bDeviceSubClass
/sys/kernel/config/usb_gadget/g1/bDeviceClass

Fix needed

/usr/bin/init_ffs (and likely usb-moded configuration) needs to be updated to use the configfs gadget API at /sys/kernel/config/usb_gadget/g1/ instead of the legacy /sys/class/android_usb/android0/ interface. An RNDIS function needs to be created under configfs for SSH mode to work.

[FlorentRevest]

/usr/bin/init_ffs (and likely usb-moded configuration) needs to be updated to use the configfs gadget API at /sys/kernel/config/usb_gadget/g1/ instead of the legacy /sys/class/android_usb/android0/ interface. An RNDIS function needs to be created under configfs for SSH mode to work.

Could you try using /usr/bin/init_gfs (https://github.com/AsteroidOS/meta-asteroid/blob/71878ed09e43cef93a86512149199526ce5e4f3f/recipes-nemomobile/usb-moded/usb-moded/init_gfs#L4) instead of init_ffs in the usb-moded systemd service https://github.com/AsteroidOS/meta-asteroid/blob/71878ed09e43cef93a86512149199526ce5e4f3f/recipes-nemomobile/usb-moded/usb-moded/usb-moded.service#L13 ?

[0x53A]

yes that works with some additional changes - I'll look into fixing this properly in usb-moded when I get some more time, in the meantime, if anyone else is following, here is a quick fix that crams usb-networking in together with adb sidestepping usb-moded:

---

Root Cause

There are actually three interacting issues:

1. android-gadget-setup takes the wrong code path

The script checks if [ -d /sys/class/android_usb/android0 ] to choose between legacy sysfs and configfs. On hoki, that directory exists as a stub — it only contains power, state, subsystem, uevent but no enable, iSerial, etc. So the script takes the legacy path and silently fails.

Fix: Check for the enable file instead:

-if [ -d $ANDROID_USB ]; then
+if [ -f $ANDROID_USB/enable ]; then
     usb_setup_android_usb
 else
     usb_setup_configfs /sys/kernel/config
 fi

This is a one-line fix that would help any device with a stub android_usb directory.

2. init_ffs crashes usb-moded

Same issue — init_ffs writes to the non-existent legacy sysfs nodes, fails with "Permission denied", and usb-moded.service enters a restart loop. Using init_gfs instead (as suggested) gets usb-moded to start.

3. usb_moded hardcodes RNDIS, but hoki only has NCM

Even with init_gfs, usb_moded's built-in configfs support tries to create rndis.rndis — which fails on hoki because the kernel doesn't have RNDIS. Only NCM (ncm.usb0) is available:

# mkdir /sys/kernel/config/usb_gadget/g1/functions/rndis.rndis
mkdir: No such file or directory
# mkdir /sys/kernel/config/usb_gadget/g1/functions/ncm.usb0
(success)

usb_moded also expects configs/b.1 but hoki's gadget (created by Android init) uses configs/c.1.

Working Solution

I bypassed usb-moded (left it disabled) and instead:

Step 1: Patch /usr/bin/android-gadget-setup

Two changes to this script:

a) Fix the detection logic (line ~67):

-if [ -d $ANDROID_USB ]; then
+if [ -f $ANDROID_USB/enable ]; then
     usb_setup_android_usb
 else
     usb_setup_configfs /sys/kernel/config
 fi

b) Add NCM to usb_setup_configfs() — create the function alongside ADB and link it into the config:

     echo $USB_FUNCTIONS | grep -q "adb" && mkdir $GADGET_DIR/g1/functions/ffs.adb

+    # NCM for USB networking (hoki kernel has NCM but not RNDIS)
+    mkdir -p $GADGET_DIR/g1/functions/ncm.usb0 2>/dev/null
+
     mkdir $GADGET_DIR/g1/configs/c.1
     ...
     echo $USB_FUNCTIONS | grep -q "adb" && ln -s $GADGET_DIR/g1/functions/ffs.adb $GADGET_DIR/g1/configs/c.1

+    # Link NCM into config
+    ln -sf $GADGET_DIR/g1/functions/ncm.usb0 $GADGET_DIR/g1/configs/c.1/ 2>/dev/null

This creates a composite ADB+NCM gadget at boot. ADB continues to work as before.

Step 2: Create /etc/systemd/system/hoki-usb-ncm.service

This service configures the watch-side IP and runs a DHCP server so the host auto-configures:

[Unit]
Description=Configure USB NCM network interface
After=android-tools-adbd.service
Wants=android-tools-adbd.service

[Service]
Type=simple
ExecStartPre=/bin/sleep 3
ExecStartPre=/bin/sh -c 'for IFACE in usb0 ncm0; do ip addr add 192.168.222.15/24 dev $IFACE 2>/dev/null && ip link set $IFACE up && break; done'
ExecStart=/usr/sbin/udhcpd -f /etc/udhcpd-usb.conf
ExecStop=/bin/sh -c 'for IFACE in usb0 ncm0; do ip addr del 192.168.222.15/24 dev $IFACE 2>/dev/null; ip link set $IFACE down 2>/dev/null; done'

[Install]
WantedBy=multi-user.target

Step 3: Create /etc/udhcpd-usb.conf

start       192.168.222.1
end         192.168.222.1
interface   usb0
opt subnet  255.255.255.0
opt lease   86400
max_leases  1

Step 4: Enable the service, disable usb-moded

systemctl daemon-reload
systemctl enable hoki-usb-ncm.service
systemctl disable usb-moded.service

Result

After reboot: plug in the watch, host gets 192.168.222.1/24 via DHCP, ssh root@192.168.222.15 works immediately. ADB also continues to work.

Upstream considerations

The detection fix (1a) is generic and would help any device with a stub android_usb directory. The NCM parts (1b, 2, 3) are hoki-specific since other devices may have RNDIS. For a proper upstream fix, usb_moded would ideally fall back to NCM when RNDIS isn't available, and meta-hoki would need a bbappend to use init_gfs instead of init_ffs.

[fluffysfriends]

It's the same on the latest nightlies for rinato as well and there is no way to access adb on that watch so for now i dont have a way to check the issue