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So, I'm trying to install Gentoo on a Dell XPS 9520 using a kernel that is configured to be as minimal as possible. So far, I've managed to get everything working, except for the touchpad.

I've booted into Kubuntu and dmesg reports

[    1.685836] intel-lpss 0000:00:15.1: enabling device (0000 -> 0002)
[    1.686228] idma64 idma64.1: Found Intel integrated DMA 64-bit
[    1.820546] input: ELAN2D24:00 04F3:2D24 Touchscreen as /devices/pci0000:00/0000:00:15.0/i2c_designware.0/i2c-1/i2c-ELAN2D24:00/0018:04F3:2D24.0001/input/input5
[    1.820871] input: ELAN2D24:00 04F3:2D24 as /devices/pci0000:00/0000:00:15.0/i2c_designware.0/i2c-1/i2c-ELAN2D24:00/0018:04F3:2D24.0001/input/input6
[    1.821015] input: ELAN2D24:00 04F3:2D24 as /devices/pci0000:00/0000:00:15.0/i2c_designware.0/i2c-1/i2c-ELAN2D24:00/0018:04F3:2D24.0001/input/input7
[    1.821262] hid-generic 0018:04F3:2D24.0001: input,hidraw0: I2C HID v1.00 Device [ELAN2D24:00 04F3:2D24] on i2c-ELAN2D24:00
[    1.822230] input: VEN_04F3:00 04F3:311C Mouse as /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-2/i2c-VEN_04F3:00/0018:04F3:311C.0002/input/input9
[    1.822506] input: VEN_04F3:00 04F3:311C Touchpad as /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-2/i2c-VEN_04F3:00/0018:04F3:311C.0002/input/input10
[    1.822841] hid-generic 0018:04F3:311C.0002: input,hidraw1: I2C HID v1.00 Mouse [VEN_04F3:00 04F3:311C] on i2c-VEN_04F3:00

Here 04F3:2D24 represents the touchscreen, and 04F3:311C the touchpad, as identified by libinput list-devices on Kubuntu. I've ascertained the drivers for both (to my surprise) the touchpad and touchscreen (i.e. ELAN2D24:00 04F3:2D24, VEN_04F3:00 04F3:311C Mouse, and VEN_04F3:00 04F3:311C Touchpad) to be hid_multitouch:

$ ls -l /dev/input/event[...]
[...]

$ cd /sys/dev/char/[major]:[minor]/device/device/driver
[...]

$ ls -al | grep module
hid_multitouch

On Gentoo, I've enabled I2C_DESIGNWARE_CORE, I2C_DESIGNWARE_PLATFORM and even I2C_DESIGNWARE_PCI (along with, of course hid_multitouch), to no avail. The module does indeed load,

$ doas lsmod
Module                  Size  Used by
intel_ishtp_hid        24576  0
iwlmvm                421888  0
hid_multitouch         28672  0
hid_generic            16384  0
mac80211              929792  1 iwlmvm
libarc4                16384  1 mac80211
dell_wmi               20480  0
dell_smbios            16384  1 dell_wmi
iwlwifi               454656  1 iwlmvm
dell_wmi_sysman        36864  0
sparse_keymap          16384  1 dell_wmi
dell_wmi_descriptor    16384  2 dell_wmi,dell_smbios
firmware_attributes_class    16384  1 dell_wmi_sysman
cfg80211              921600  3 iwlmvm,iwlwifi,mac80211
x86_pkg_temp_thermal    20480  0
i2c_i801               28672  0
thunderbolt           286720  0
i2c_smbus              16384  1 i2c_i801
i2c_designware_platform    16384  0
i2c_designware_core    28672  1 i2c_designware_platform
idma64                 20480  0
intel_ish_ipc          28672  0
intel_ishtp            57344  2 intel_ishtp_hid,intel_ish_ipc
wmi                    28672  4 dell_wmi_sysman,dell_wmi,dell_smbios,dell_wmi_descriptor
i2c_hid_acpi           16384  0
i2c_hid                28672  1 i2c_hid_acpi
rtc_cmos               24576  1
efivarfs               16384  1
zfs                  4161536  8
zunicode              335872  1 zfs
zzstd                 569344  1 zfs
zlua                  180224  1 zfs
zavl                   16384  1 zfs
icp                   323584  1 zfs
zcommon               102400  2 zfs,icp
znvpair               106496  2 zfs,zcommon
spl                   110592  6 zfs,icp,zzstd,znvpair,zcommon,zavl
xhci_pci               20480  0
xhci_hcd              258048  1 xhci_pci

but only seems to drive the touchscreen.

A further curiosity is that the Kubuntu kernel seems to do fine without, relying only upon i2c and hid drivers (yet, it somehow still reports i2c_designware.0 and i2c_designware.1 in the dmesg log).

I'm at my wits' end when it comes to this and have no clue as to how to proceed. I'm very new to Linux; help is much appreciated.

Edit: Occasionally, upon rebooting, using the touchpad produces a seemingly random stream of characters on the TTY.

1 Answer 1

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The Gentoo discussion forums users' provided the following answer, which was linked to me on my own question there. For future reference:

There appears to be a bug in the Alder Lake pin control driver merged in 5.18.15. Instead, enable the Tiger Lake drivers. Additionally, only

  • Synopsys DesignWare Platform (I2C_DESIGNWARE_PLATFORM)
  • HID over I2C transport layer ACPI (I2C_HID_ACPI) and
  • hid_multitouch (HID_MULTITOUCH)

drivers are necessary. Not necessary are:

  • DesignWare PCI
  • LPSS (which is a general-purpose I2C driver)
  • SMBus
  • GPIO
  • Input Device Support
    • Touchscreens
    • Mice, and other drivers

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