x86/64: iTCO_wdt watchdog non-functional on Intel 100+ series PCH due to missing CONFIG_I2C_I801

Package Name

kmod-itco-wdt

Maintainer

OpenWrt Kernel Team

OpenWrt Version

24.10.6

OpenWrt Target/Subtarget

x86/64

Steps to Reproduce

1. Install OpenWrt 24.10.x on an Intel 100/200 series PCH platform
   (tested on HP EliteDesk 800 G3, Q270 chipset, Pentium G4560)

2. Install the watchdog package:
   opkg update && opkg install kmod-itco-wdt

3. Reboot and check for /dev/watchdog:
   ls -la /dev/watchdog

4. Observe: /dev/watchdog does NOT exist

5. Check kernel log:
   dmesg | grep -iE "iTCO|watchdog|i801"

Output shows iTCO_wdt loads but reports no TCO device found:
iTCO_wdt: No TCO device found

6. On Intel 100+ series PCH (Sunrise Point and newer), the iTCO_wdt
   platform device is created by the i2c_i801 SMBus driver, NOT lpc_ich.

7. The i2c-i801.ko module is available in the OpenWrt SDK but is NOT
   listed as a dependency of kmod-itco-wdt, so it is never installed.

8. Manually loading i2c-i801.ko immediately fixes the issue:
   insmod i2c-smbus.ko insmod i2c-i801.ko modprobe iTCO_wdt ls -la /dev/watchdog # Now exists!

dmesg shows:
i801_smbus 0000:00:1f.4: SMBus using PCI interrupt iTCO_wdt iTCO_wdt: Found a Intel PCH TCO device (Version=4, TCOBASE=0x0400)

Actual Behaviour

On Intel 100+ series PCH platforms:

• kmod-itco-wdt installs and loads successfully
• But /dev/watchdog is never created
• dmesg shows "iTCO_wdt: No TCO device found" or similar

Root cause: On Intel Sunrise Point (100 series) and newer consumer PCH
chipsets, the iTCO_wdt platform device is created as an MFD cell by the
i2c_i801 SMBus driver. The legacy lpc_ich path no longer applies.

Since kmod-i2c-i801 is not a dependency of kmod-itco-wdt, the SMBus
driver is never installed, the TCO platform device is never registered,
and /dev/watchdog never appears.

Affected chipsets include but are not limited to:

• Intel 100 series: Q170, Q270, B250, Z270, H270 (Sunrise Point)
• Intel 200 series: Q370, B360, Z390 (Cannon Lake PCH)
• Intel 300 series and newer consumer PCH

Proposed fix: Add the following dependency to kmod-itco-wdt:
DEPENDS:=+kmod-i2c-i801

Confirmation Checklist

• The package is maintained in this repository.
• I understand that issues related to the base OpenWrt repository or LuCI repository will be closed.
• I am reporting an issue for OpenWrt, not an unsupported fork.

Inspect the package definition for kmod-itco-wdt and its dependency metadata; the issue identifies kmod-i2c-i801 as the missing dependency. Reproduce the package installation on an affected Intel 100-series-or-newer platform, then verify that installing kmod-itco-wdt also provides the SMBus module and creates /dev/watchdog without manual insmod steps.