[SRU][R][PATCH 0/1] UBUNTU: SAUCE: drm/i915/tc: Revert forced DP-alt connected workaround

[ChunAn Wu]

BugLink: https://bugs.launchpad.net/bugs/2160082


[Impact]
On systems with Intel display and Type-C ports, real USB-C/TBT dock
unplug events can leave the driver reporting the port as connected.
The driver then issues real AUX transactions against a removed sink
and spends seconds in repeated -ETIMEDOUT retries, causing display
stalls/freezes.

The root cause is a prior SAUCE workaround (commit e9cdae7685d7) that
forced intel_tc_port_connected() to return true whenever a TC port
had an active link reference, was in DP-alt mode, and the display
still owned the PHY. That heuristic uses driver/ownership state
rather than live sink presence, so on a genuine unplug the PHY can
remain owned while the sink is already gone, and the disconnected-
port AUX fast-fail path never runs.

[Fix]
Revert the SAUCE workaround so TC port connected state is again
based on live HPD status. Real disconnects then return -ENXIO from
the AUX guard immediately instead of stalling in AUX retries.

The original transient HPD issue on the HP Type-C to HDMI dongle
(LP: #2143879) that motivated the workaround is already fixed in
TC firmware, so the kernel workaround is no longer required.

[Test Case]
On an affected platform with a USB-C/TBT dock or DP-alt sink:
  1. Boot and connect a display via the dock.
  2. Physically unplug the dock/sink.
  3. Verify the desktop does not stall/freeze and the display is
     reported disconnected promptly (no multi-second AUX -ETIMEDOUT
     bursts in dmesg).
  4. Reconnect and confirm normal detection/enablement still work.

[Regression Potential]
Limited to Intel i915 TC port hotplug/detect paths. If the TC
firmware fix is not present on some units, the original transient
disconnect during long HPD pulses (LP: #2143879) could re-appear.
Regressions would show up as spurious short disconnects on TC
displays; mitigation is to re-apply the workaround on affected
firmware.

ChunAn Wu (1):
  [SRU][R][PATCH 1/1] UBUNTU: SAUCE: drm/i915/tc: Revert forced DP-alt
    connected workaround

 drivers/gpu/drm/i915/display/intel_tc.c | 5 -----
 1 file changed, 5 deletions(-)

-- 
2.34.1