Missing scan results with SCAN_FLAG_COLOCATED_6GHZ set (Ath11k/WCN6855)

[James Prestwood]

Hi,

I've noticed that when setting the colocated flag much of the scan 
results are not appearing when they should be. This was seen in a large 
warehouse where our network/SSID was using only the 6ghz band. There 
were other networks on 2.4/5ghz though, which maybe is having some 
effect, but those networks are not broadcasting on 6ghz.

This first came to my attention when the majority of our clients were 
experiencing horrible signal quality. Upon looking at the logs and 
nl80211 messages to the kernel IWD was issuing both limited 6ghz scans 
as well as full spectrum scans and only showing a few 6ghz results, like 
1-2 BSS's which should not have been the case. I was able to scan 
manually using "iw scan" and I saw all the expected BSS's. I isolated it 
to the fact that IWD was setting the SCAN_FLAG_COLOCATED_6GHZ and 
removing that flag resulted in all the BSS's showing up in scan results. 
Note, that with or without the flag all the 2.4/5ghz BSS's were showing 
up without a problem, it seems completely isolated to the 6ghz band.

The NEW_SCAN_RESULTS event was indicating the kernel had scanned all the 
expected frequencies we were asking to scan, but the results were mostly 
empty for 6ghz. Only ever the connected BSS would show up and 
_sometimes_ another BSS, but generally not.

I'm trying to read through the code associated with the COLOCATED flag, 
but its not exactly intuitive (to me at least). I'm not sure if this is 
something with mac80211 or at the driver level. I really don't have 
anything to compare it to as ath11k is the only hardware available at 
this warehouse with many APs around.

I'm looking for some guidance on if this is expected behavior with the 
colocated flag, and if there is any concern with including it 
unconditionally on every scan. If it has unintended consequences like 
this, generally, across multiple drivers I'd like to re-think its use in 
IWD.

Thanks,

James