brcmfmac having problems in AP + station mode
In Ironman the brcmfmac wifi is being used in both AP and station mode at the same time. "iw list" shows this configuration is supported. However, if you bring up wlan0 and uap0 as has been done with other wifi dongles the brcmfmac will disconnect the station (wifi client) when it brings up the AP. This seems to be the same as other dongles and the solution was
- bring up wlan0
- bring up uap0
- bring up wlan0 again
But the last step doesn't work with brcmfmac. There is a possible solution here but I've not tried it yet. Some googling shows this driver disables the the station when ap is started and doesn't allow it to come back up. A fix was posted in 2018 but that doesn't appear to be in either RPi Linux 4.19.y or next branch. Not sure if there is a driver fix anywhere else.
Barring a driver fix and the potential workaround fixing this I'll have to disable brcmfmac in Ironman and use a dongle. Disabling will have to include removing or renaming the driver because S10mdev will load the driver automatically if it's there and simply rmmod'ing the driver later will cause the dongle to come up as wlan1, which we don't want.