surface-touch-omarchy

Touchscreen and Surface Pen support for the Surface Pro 7 on a stock Arch / Omarchy kernel, without switching to the linux-surface kernel.

Normally, Surface touch on Linux needs the linux-surface kernel, because the touch driver (IPTS) isn't in the mainline kernel. This package builds that same driver as a DKMS module instead. It also adds a small boot service that does at runtime what the linux-surface kernel patches do at build time. Your distro kernel stays as it is.

Status: works on one machine. It has been tested only on a Surface Pro 7 (SKU 1866) with linux-omarchy 7.2.5. Reports from other setups are welcome. Please open an issue either way.

What works

• Multi-touch finger input
• Surface Pen: inking, pressure, hover, side button, eraser
• Palm rejection (optional, see Palm rejection)
• Suspend/resume
• Survives reboots, and DKMS rebuilds the module automatically on kernel updates

Not yet tested: other Surface models.

App support varies. Some apps handle pen input poorly. Pinta, for example, ignores the eraser end and can break up lines. Xournal++, Rnote and Krita work well. See Pen troubleshooting.

Requirements

• A Surface whose touch controller is Intel 8086:34e4 at PCI 00:16.4. Check with:

  lspci -nn -s 00:16.4
  

  If that prints nothing, or shows a different ID, this package won't work on your device as it is.
• Headers for the kernel you run (Omarchy: linux-omarchy-headers; stock Arch: linux-headers).
• An Arch-based distro.

Install

sudo pacman -S --needed base-devel git meson linux-omarchy-headers   # or linux-headers
git clone https://github.com/ChowderTV/surface-touch-omarchy
cd surface-touch-omarchy
makepkg -si
reboot

The build downloads iptsd's source and pinned dependencies, plus the IPTS driver from the linux-surface repo, pinned to a fixed commit and checked by checksum.

After the reboot, check that it's running:

systemctl status surface-touch 'iptsd@*'

Uninstall

sudo pacman -R surface-touch-omarchy
reboot

How it works

Piece	What it does
ipts (DKMS, installed to /usr/src/ipts-6.19)	The IPTS kernel driver, taken unchanged from linux-surface's patches/6.19/0005-ipts.patch
iptsd 3.1.0	The userspace daemon that turns raw touch/pen data into input events
surface-touch.service → /usr/lib/surface-touch/setup	Runs once at boot (details below)

The linux-surface kernel patches change two things in the kernel that we can't change from outside it. The setup script gets the same result at runtime instead:

1. mei_me doesn't know the touch chip. Mainline mei_me has no entry for 8086:34e4. The script adds the ID through /sys/bus/pci/drivers/mei_me/new_id with config index 9 (MEI_ME_PCH12_CFG, the config linux-surface uses).
2. The IOMMU blocks the touch chip's memory access. linux-surface adds a kernel quirk for this. The script instead switches only the touch chip's IOMMU group to identity (passthrough) mode, so you don't need to turn off the IOMMU globally with intel_iommu=off.

Then it loads ipts, and iptsd's udev rule starts the daemon.

Caveats (please read)

• Kernel updates could break it. The 9 in step 1 is a position in an internal kernel list (mei_cfg_list in drivers/misc/mei/pci-me.c). If a future kernel reorders that list, touch could stop working or misbehave. If touch breaks after a kernel update, check that first.
• Less isolation for one device. Passthrough mode means the IOMMU no longer restricts DMA from the devices in that group (the touch chip and the main Intel ME). It's narrower than intel_iommu=off, but it's still a security trade-off you should know about.
• The driver is tied to linux-surface's 6.19 patch. If a future kernel changes an API the driver uses, the DKMS build will fail. You'd then need to update _ls_commit to a newer linux-surface patch.

Palm rejection

By default, a resting hand can still register as touches while you write. To ignore all finger and palm touches while the pen is near the screen:

sudo cp /usr/share/doc/surface-touch-omarchy/60-palm-rejection.conf.example /etc/iptsd.d/60-palm-rejection.conf
sudo systemctl restart 'iptsd@*'

Touch comes back as soon as the pen moves away. To undo it, delete the file and restart iptsd again.

Pen troubleshooting

• Lines break up or the eraser does nothing in one app: try another app first. Pinta, for example, doesn't support the eraser end. Xournal++, Rnote and Krita do.
• Pen does nothing or lines break up: replace the pen's AAAA battery first. Bluetooth pairing only powers the top button. Inking runs on the battery, and a weak one makes the pen stop transmitting mid-stroke.
• Lines still break in a good app with a good battery: iptsd may be dropping contact because the pressure signal is near its threshold. Try lowering it:

  sudo surface-pen-tune 3000     # iptsd default is 10000

  This writes /etc/iptsd.d/50-pen-sensitivity.conf and restarts iptsd. If the pen starts inking while it's only hovering, raise the number. An example config is in /usr/share/doc/surface-touch-omarchy/.
• Wobbly lines: iptsd sends the raw pen position and leaves smoothing to apps. In Xournal++, turn it on under Edit → Preferences → Input System → Input stabilization. In Krita, set Brush Smoothing to Stabilizer in the brush Tool Options.
• To capture raw device data for a bug report: sudo iptsd-dump /dev/hidrawN (find N with systemctl list-units 'iptsd@*')

Credits

All the hard work is by the linux-surface project: the IPTS driver and iptsd. This repo only packages them so they run on an unpatched kernel. Please report bugs in this packaging here, not to linux-surface.

License

GPL-2.0-or-later, the same license as the IPTS driver and iptsd.