Public bug reported:

BugLink: http://bugs.launchpad.net/bugs/2161964

[ Impact ]

On a Strix Halo platform, we've observed that a hang (that leads to a
sync flood) can occur on shutdown when a TBT3 device is connected. We
also found that this can be fixed by asserting the DPR bit in the Port
Capability Register on shut down can fix this issue. This behavior also
aligns with other what other operating system does.

[ Fix ]

Cherry-pick the following commit from upstream:

- thunderbolt: Assert downstream port reset on shutdown[1]

Which is already in linux-next.

[ Test cases ]

Boot the new kernel, plug the thunderbolt storage and run `systemctl
poweroff -i`. The system should shutdown.

[ Where the problems could occur ]

This essentially proactively disconnects the USB4 link manually during
kernel shutdown, but the USB4 devices are getting powered off anyway, so
functionally should not impact the devices.

[ Additional Information]

[1] 
https://lore.kernel.org/all/[email protected]/
[2] USB4 spec: 6.9 Downstream Facing Port Reset

** Affects: linux-oem-7.0 (Ubuntu)
     Importance: Undecided
     Assignee: Leo Lin (0xff07)
         Status: New

** Changed in: linux-oem-7.0 (Ubuntu)
     Assignee: (unassigned) => Leo Lin (0xff07)

** Description changed:

+ BugLink: http://bugs.launchpad.net/bugs/2161964
+ 
  [ Impact ]
  
  On a Strix Halo platform, we've observed that a hang (that leads to a
  sync flood) can occur on shutdown when a TBT3 device is connected. We
  also found that this can be fixed by asserting the DPR bit in the Port
  Capability Register on shut down can fix this issue. This behavior also
  aligns with other what other operating system does.
- 
  
  [ Fix ]
  
  Cherry-pick the following commit from upstream:
  
  - thunderbolt: Assert downstream port reset on shutdown[1]
  
  Which is already in linux-next.
  
- 
  [ Test cases ]
  
  Boot the new kernel, plug the thunderbolt storage and run `systemctl
  poweroff -i`. The system should shutdown.
- 
  
  [ Where the problems could occur ]
  
  This essentially proactively disconnects the USB4 link manually during
  kernel shutdown, but the USB4 devices are getting powered off anyway, so
  functionally should not impact the devices.
  
- 
  [ Additional Information]
  
  [1] 
https://lore.kernel.org/all/[email protected]/
  [2] USB4 spec: 6.9 Downstream Facing Port Reset

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https://bugs.launchpad.net/bugs/2161964

Title:
  [SRU] Fix hang on shutdown with TBT3 connected

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