watchthelight labs

[Arrow Lake] Support for Touchpad on I2C '7F7A' (not 7F7C as previously mentioned ;) ) #4

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Chiledog 2026-10-28

If possible could we get support for touchpads on Arrow Lake platforms that are connected to the 7F7A I2C bus?

I2C-7F7A

chiledog@laptop-umk3cle71 ~ % ioreg -r -n I2C0 -l | grep device-id
"device-id" = <4c7f0000>
chiledog@laptop-umk3cle71 ~ % ioreg -r -n I2C1 -l | grep device-id
chiledog@laptop-umk3cle71 ~ % ioreg -r -n I2C2 -l | grep device-id
chiledog@laptop-umk3cle71 ~ % ioreg -r -n I2C3 -l | grep device-id
chiledog@laptop-umk3cle71 ~ % ioreg -r -n I2C4 -l | grep device-id
"device-id" = <7a7f0000>

chiledog@laptop-umk3cle71 ~ % ioreg -r -c VoodooI2CPCILakeController -l -w0
chiledog@laptop-umk3cle71 ~ %

chiledog@laptop-umk3cle71 ~ % log show --predicate 'process == "kernel"' --last 10m | grep -E "VoodooI2C|IOHD"
2026-10-28 11:48:04.392192+0100 0x483 Default 0x0 0 0 kernel: Couldn't alloc class "VoodooI2CPCILakeController"
2026-10-28 11:48:04.392556+0100 0x566 Default 0x0 0 0 kernel: Couldn't alloc class "VoodooI2CPCILakeController"
chiledog@laptop-umk3cle71 ~ %

Chiledog 2026-10-28

I'll grab the extra info from osx and add.

watchthelight 2026-10-28

Thanks, that log helps. "Couldn't alloc class VoodooI2CPCILakeController" means 1.2.0 did match your 7F7A (and the 7F4C on I2C0), but the VoodooI2C you have loaded has no class by that name. VoodooI2C master removed it in November 2025 (054d5d1), so I think you're on a master or nightly build.

Two ways out:

  1. Use the VoodooI2C 2.9.1 release and keep VoodooI2CHID from the same release. That's the only setup I've tested.
  2. Or stay on master and change IOClass in LegionI2CArrowLake.kext/Contents/Info.plist from VoodooI2CPCILakeController to VoodooI2CPCIController in both 7F7A personalities. An ASUS FX608LP owner reports that works on master; I haven't run it myself.

Either way keep -vi2c-force-polling in boot-args. Could you post the output of kmutil showloaded | grep -i voodoo so I can see which version is loaded, and after the change ioreg -r -c VoodooI2CHIDDevice | head?

Chiledog 2026-10-28

Changing kexts worked!

Pre-kext-2.9.1

chiledog@laptop-umk3cle71 ~ % kmutil showloaded | grep -i voodoo
No variant specified, falling back to release
64 1 0xffffff8004daf000 0x13000 0x13000 com.alexandred.VoodooI2CServices (1) B9FE9E08-E3BF-311D-8200-A52D7A41591A <6 3>
103 1 0xffffff8004dc2000 0x63000 0x63000 org.coolstar.VoodooGPIO (1.1) DD79D78E-EA67-3822-B990-B3CD1E1705B9 <17 7 6 3>
104 0 0xffffff8004e25000 0x29000 0x29000 com.alexandred.VoodooI2C (2.9.1) 0BD5308D-DEC0-3117-8BF3-522F218A0E6A <103 64 59 19 17 7 6 3 1>
chiledog@laptop-umk3cle71 ~ %

With kext 2.9.1 you linked

chiledog@laptop-umk3cle71 ~ % kmutil showloaded | grep -i voodoo
No variant specified, falling back to release
64 1 0xffffff8004daf000 0x13000 0x13000 com.alexandred.VoodooI2CServices (1) B9FE9E08-E3BF-311D-8200-A52D7A41591A <6 3>
103 1 0xffffff8004dc2000 0x4e000 0x4e000 org.coolstar.VoodooGPIO (1.1) 6D611A79-9990-34AB-8D14-C0EC9845EE37 <17 7 6 3>
104 1 0xffffff8004e10000 0x2b000 0x2b000 com.alexandred.VoodooI2C (2.9.1) 49691D8A-EA92-32CE-A2FD-24AD6DDF45A6 <103 64 59 19 17 7 6 3 1>
105 0 0xffffff8004f49000 0x3b000 0x3b000 com.alexandred.VoodooI2CHID (1) 84ED0F48-9496-3ABA-8058-728AD4BC492A <104 59 17 7 6 3>
111 0 0xffffff8004f2e000 0x1b000 0x1b000 me.kishorprins.VoodooInput (1.1.6) B5BEA2C9-6254-313A-BE09-4778DBB28F3E <59 7 6 3>
chiledog@laptop-umk3cle71 ~ %

chiledog@laptop-umk3cle71 ~ % ioreg -r -c VoodooI2CHIDDevice | head
+-o VoodooI2CHIDDevice <class VoodooI2CHIDDevice, id 0x100000435, registered, matched, active, busy 0 (19008 ms), retain 11>
| {
| "IOMatchedAtBoot" = Yes
| "HIDDescriptorAddress" = 1
| "MaxInputReportSize" = 64
| "PrimaryUsagePage" = 1
| "VersionNumber" = 1281
| "ReportDescriptor" = <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>
| "VendorID" = 10248
| "IOUserClientClass" = "IOHIDLibUserClient"

Thank you!

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