[Bug 208893] Navi (RX 5700 XT) system appears to hang with more than one display connected

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=208893

--- Comment #12 from Gordon (gordon at gordonite.tech) ---
I'm not certain but:
- uint32_t cur_value, i, timeout = adev->usec_timeout * 10;

if adev_usec_timeout is the microseconds timeout, then most likely the * 10 is
wrong, as the below for loop uses microseconds too, so possibly they meant to
add there too. Each iteration is 1 micro second, and the below code makes it 10
times that for the timeout, i think this explains the 'hanging' but not why it
inconsistently breaks.

Another few thoughts were:
- Perhaps there is a period of messages on 'init' / startup where we are
sending more.
- I can only think the flaky behaviour is a memory issue, or a problem where
the GPU is not being reset fully on boot. As it makes zero sense it works
'sometimes'.
- When the message / error occours the 'timeout' is 10 times the value, thus
blocking messages for the other startup events.
- The display port being connected / or being interfaced with on init might be
preventing the normal startup messages to be sent to the GPU.

These GPUs have a problem in general with loss of display output, so if there
is an electronics issue, maybe we don't have the 'hack' to make it work.

IDK for sure, I'm new to kernel devel. I mainly work on Godot.

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