IBSS (AdHoc) does not work on RPI 3B+ (and possibly others)

[darkdrgn2k]

Can't seem to configure pi into IBSS (AdHoc) mode

$ sudo  iwconfig wlan0 mode ad-hoc essid my-mesh ap 02:12:34:56:78:9A channel 1
Error for wireless request "Set Mode" (8B06) :
    SET failed on device wlan0 ; Device or resource busy.

$ dmesg
brcmf_cfg80211_change_iface: iface validation failed: err=-16

Running Laters Raspbian and also rpi-update 4.14.56-v7+

[popcornmix]

Duplicate of raspberrypi/firmware#990 ?

[darkdrgn2k]

Could also be a re-surfacing of #1384

Not sure if its a Firmware issue or a Kernel Issue.

[popcornmix]

It's not a (gpu) firmware issue (that has no knowledge of wifi).
I don't know enough to say if it's a kernel issue (possibly the wifi firmware) or a linux configuration issue.

[JamesH65]

This issue will be closed within 30 days unless further interactions are posted. If you wish this issue to remain open, please add a comment. A closed issue may be reopened if requested.

[JamesH65]

Closing due to lack of activity. Please request to be reopened if you feel this issue is still relevant.