[invaliddayta]

I declared it at 7 am and you had it evaluated by lunch. Most reproducible wish I've ever made.

On a MacBook Air M2 (J413, T8112), a USB-C monitor in one port leaves a DP Alt Mode dock in the other port without USB. The dock's hub (VIA Labs 2109:2817/0817) enumerates for a moment and then disappears, and the port never gets a USB role back:

xhci-hcd xhci-hcd.3.auto: remove, state 1
phy-apple-atc 383000000.phy: Pipehandler lock not acked.
phy-apple-atc 383000000.phy: Failed to lock pipehandler
tps6598x 0-0038: failed to configure Type-C connection: -28
tps6598x 0-0038: failed to configure Type-C connection: -28
tps6598x 0-0038: failed to configure Type-C connection: -28
tps6598x 0-0038: cable revalidation failed after 3 attempts

Cause:

• T8112 has one external display pipeline, and the monitor holds it. The DCP fabric reports that as -ENOSPC on every SoC (dcp_typec_route_set()).
• c1ef888 made -ENOSPC the error that means "display taken": tipd then sets up the port's USB without the display and does not retry.
• dea3f3b kept that on T8140/T8142 only, and made -EBUSY the taken display on every other SoC. So on T8112, -ENOSPC is retried until revalidation gives up, and usb_role_switch_set_role() is never reached.

Fix: go back to the one meaning on every SoC: cd321x_display_taken() is ret == -ENOSPC again, and the KUnit case expects that. I could not find a route in this tree that still reports a taken pipeline as -EBUSY. The remaining -EBUSY sources on that mux chain are the ATC PHY's transitions, which c1ef888 wants retried. h17_display stays, because the H17 HPD rules use it.

If the -EBUSY branch for the older SoCs was there for a reason I missed, the narrower alternative is ret == -ENOSPC || (!h17 && ret == -EBUSY). That keeps it and still fixes the dock.

Tested on J413 (MacBook Air M2, T8112):

• Kernel: 7.2.10 at 1b4997b (what aurora-silicon/nixos-aurora pins) plus this patch, built with aurora-silicon/nixos-aurora's kernel derivation (its nixpkgs, config and LLVM 22). Without the patch, it evaluates to the same derivation as the kernel in their cache.
• Distribution: NixOS. m1n1 omacom d05ba17, sway.
• Devices:
  • a USB-C monitor (5120x1440 at 60 Hz, DP Alt Mode, with its own USB hub);
  • a USB-C dock (VIA Labs hub, DP Alt Mode, no display on it) with a mouse, a keyboard and Ethernet.
• Before: with the monitor already plugged in, the dock got no USB in 3 of 3 plugs, on either port. Each time: cable revalidation failed after 3 attempts.
• After (one boot, about 4 minutes of replugging in both orders and on both ports):
  • 10 of 10 -28 events were followed by USB on that port within 3 s;
  • no revalidation gave up;
  • the dock's keyboard, mouse and Ethernet worked;
  • the monitor stayed at 5120x1440.
• Known limit, not changed here: each plug brings the dock's USB up, tears it down for the DP mode switch about a second later, then brings it up again. In 3 of those cycles, a mouse that was enumerating behind the dock's hub got stuck (device descriptor read/64, error -32, then device not accepting address 6, error -71) until it was replugged.
• KUnit (tools/aurora-ci/run-kunit.py on 34c7dfe plus this patch, arm64 under QEMU TCG): 1396 pass, 0 fail, 3 skip, which matches kunit-expected.json.
• checkpatch.pl --strict: 0 errors, 0 warnings.

Written with an AI assistant (Assisted-by trailer). I reviewed it and tested it on the machine above.