media: ipu7: register the psys bus before adding devices#89
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ipu7_psys_bus is defined and assigned to psys->dev.bus, but is never passed to bus_register(). device_register() on a device whose bus was never registered depends on the kernel's tolerance for that condition; newer kernels reject it outright with -EINVAL: bus_add_device: cannot add device 'ipu7-psys0' to unregistered bus 'intel-ipu7-psys' intel-ipu7-psys ipu7-psys0: psys device_register failed intel_ipu7_psys.psys intel_ipu7.psys.40: probe with driver intel_ipu7_psys.psys failed with error -22 which breaks PSys probe entirely and /dev/ipu7-psys0 is never created. Reproduced on CachyOS kernel 7.1.3 (IPU7, ThinkPad X9-14/Lunar Lake); the same tree still probed successfully on kernel 7.0.11. Register ipu7_psys_bus in module init before registering the auxiliary driver, and unregister both in reverse order on exit.
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Summary
ipu7_psys_bus(drivers/media/pci/intel/ipu7/psys/ipu-psys.c) is defined and assigned topsys->dev.businipu7_psys_probe(), but is never passed tobus_register(). Callingdevice_register()on a device whosebuswas never registered relies on kernel tolerance for that condition; newer kernels reject it outright:This makes PSys probe fail entirely, so
/dev/ipu7-psys0is never created and any hardware-ISP pipeline (e.g.icamerasrc) fails withnot-negotiated.Reproduced on a ThinkPad X9-14 (Lunar Lake, IPU7) running CachyOS. PSys probed and streamed correctly on kernel 7.0.11 but started failing after upgrading to kernel 7.1.3 — no other driver, firmware, or config changes involved, so this looks like a kernel-side tightening of
bus_add_device()behavior that exposed a pre-existing bug in this driver.Fix
Replace the
module_auxiliary_driver()convenience macro with explicitmodule_init/module_exitfunctions thatbus_register(&ipu7_psys_bus)before registering the auxiliary driver, and unregister both in reverse order on exit.Test plan
make LLVM=1 KERNELRELEASE=7.1.3-2-cachyos KERNEL_SRC=/lib/modules/7.1.3-2-cachyos/buildbuilds cleanlyintel_ipu7_psys—/dev/ipu7-psys0now appearsgst-launch-1.0 icamerasrc ! video/x-raw,format=NV12,width=1920,height=1080 ! fakesinknegotiates caps and streams without error (previously failed withnot-negotiated (-4))