[Bug 219748] Pluggable UD-4VPD dock appears to continually reset with AMD AI 365

bugzilla-daemon
2025-03-07T10:39:47Z

--- Comment #31 from Mika Westerberg (mika.westerberg@linux.intel.com) ---
(In reply to Mario Limonciello (AMD) from comment #30)
> > I'm leaving the graphics side for Mario to comment on as I'm not qualified.
> I
> > do see MST and that seem to be problematic in Linux IIRC.
>
> My main worry is if the retimer scan is the reason for the DPIA issues too.
> The report that Sean linked in was a failing to read an EDID which got fixed
> by pushing the scan later.
>
> So if you can reproduce the display issues try with it commented out
> entirely (maybe we want that for debugging as a module parameter Mika?).

I'm not convinced that retimer scanning has anything to do with that issue. It
does affect timing when the device router is enumerated and that's the issue
with Pluggable, they have implemented some sort of non-standard timeout there.

The other issue happens long after device router is already enumerated and the
DP tunnels are established. The patch may seem to "solve" the issue but it
probably just hides the real one and this is what we need to understand.

Therefore I suggest to open a separate issue for that one with appropriate full
dmesg and the repro steps, CC me too I can take a look. We can defer this fix
until we understand the real problem but let's keep the two separate.