PSYS DKMS module permanently defers on kernel 7.0-rc7 (in-tree ISYS)

[jibsta210]

Summary

The PSYS DKMS module from intel-ipu7-dkms-git permanently defers probe when used alongside the in-tree IPU7 ISYS driver on kernel 7.0-rc7. This means the hardware ISP is unusable, forcing users to fall back to libcamera's software ISP (~65% CPU, poor image quality).

Environment

• Dell XPS with Intel Panther Lake
• CachyOS, kernel 7.0.0-rc7-2-cachyos-rc (IPU7 ISYS is in-tree)
• Sensor: OV08X40 (OVTI08F4)
• Bridge: Synaptics SVP7500 USBIO
• AUR packages: intel-ipu7-camera-bin, intel-ipu7-dkms-git, intel-ipu7-camera-hal-git

Problem

The DKMS PSYS module checks adev->isp->ipu7_bus_ready_to_probe in ipu-psys.c (line ~1345). While this field does exist in the in-tree struct ipu7_device and is set to true at the end of successful probe in ipu7.c, PSYS appears to probe before the parent driver completes, seeing the flag as false and returning -EPROBE_DEFER.

Attempting to patch out the check (if (0) instead of if (!adev->isp->ipu7_bus_ready_to_probe)) results in a kernel crash (SIGKILL), suggesting deeper ABI/structural incompatibilities between the DKMS PSYS module and the in-tree ISYS driver.

dmesg output

intel_ipu7_psys: probe of intel_ipu7_psys.0 deferred
# Never resolves - permanently deferred

Current workaround

Blacklist PSYS and use libcamera's software ISP:

# /etc/modprobe.d/ipu7-usbio-order.conf
blacklist intel_ipu7_psys

Then relay through GStreamer + v4l2loopback for browser compatibility.

Request

Could you provide guidance on:

1. Whether the DKMS PSYS module is expected to work with the in-tree 7.0-rc7 ISYS driver?
2. If not, what kernel version / driver combination is required for PSYS to work?
3. Whether there are plans to upstream PSYS to the mainline kernel?

Full guide

I've documented the complete workaround (software ISP path) for others hitting this issue:
https://www.reddit.com/r/cachyos/ (search for "IPU7 camera guide")

[jibsta210]

Update: Found the root cause and a fix.

The DKMS PSYS module crashes (not just defers) when used with the in-tree 7.0-rc7 ISYS driver. The issue is a struct ipu7_device layout mismatch:

• DKMS ipu7.h has struct dentry *ipu7_dir (under #ifdef CONFIG_DEBUG_FS) between pb_base and hw_ver
• In-tree ipu7.h lacks this field entirely

This shifts hw_ver, ipc_reinit, secure_mode, and ipu7_bus_ready_to_probe by 8 bytes. When PSYS reads ipu7_bus_ready_to_probe, it gets garbage → EPROBE_DEFER. When it reaches ipu7_psys_init_debugfs, it reads hw_ver+bools as a pointer (0x0000000001010002) and page faults.

Fix (one line in psys/ipu-psys.c):

- dir = debugfs_create_dir("psys", psys->adev->isp->ipu7_dir);
+ dir = debugfs_create_dir("ipu7-psys", NULL);

With this patch, PSYS loads and the hardware ISP works correctly on kernel 7.0-rc7 with the in-tree ISYS driver. Tested on Dell XPS 16 (Panther Lake), OV08X40 sensor.

Could the DKMS package be updated to handle the case where the in-tree driver lacks ipu7_dir? Something like:

#ifdef CONFIG_DEBUG_FS
    struct dentry *parent = psys->adev->isp->ipu7_dir;
    dir = debugfs_create_dir("psys", parent);
#endif

...won't work because the field itself doesn't exist in the in-tree struct. The DKMS headers would need to be updated to match the in-tree layout, or the in-tree driver would need to add the ipu7_dir field.