kern/56478: unused wm0 periodically prints "device timeout" and causes kernel latency

[nia%pkgsrc.org@localhost]

>Number:         56478
>Category:       kern
>Synopsis:       unused wm0 periodically prints "device timeout" and causes kernel latency
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Oct 31 08:05:00 +0000 2021
>Originator:     nia
>Release:        NetBSD 9.99.92 amd64
>Organization:
The NetBSD Foundation, Inc
>Environment:
NetBSD 9.99.92 amd64
>Description:
booting with dhcpcd=YES, with no cable plugged into my wm0, it
periodically spams dmesg:

[  1152.784855] wm0: device timeout (txfree 4032 txsfree 0 txnext 76)
[  1176.035005] wm0: device timeout (txfree 4032 txsfree 0 txnext 79)
[  1201.285172] wm0: device timeout (txfree 4032 txsfree 0 txnext 76)

until `ifconfig wm0 down`.

It causes audio skipping until the ifconfig down,
presumably due to a spike in system load.
>How-To-Repeat:

>Fix: