Alvin Šipraga [off-list ref] wrote:

The sinfo->chains field is a bitmask for filled values in chain_signal
and chain_signal_avg, not a count. Treat it as such so that the driver
can properly report per-chain RSSI information.

Before (MIMO mode):

  $ iw dev wlan0 station dump
      ...
      signal: -51 [-51] dBm

After (MIMO mode):

  $ iw dev wlan0 station dump
      ...
      signal: -53 [-53, -54] dBm

Fixes: cae355dc90db ("brcmfmac: Add RSSI information to get_station.")
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>

2 patches applied to wireless-drivers-next.git, thanks.

feb456437621 brcmfmac: fix setting of station info chains bitmask
9a1590934d9a brcmfmac: correctly report average RSSI in station info

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210506132010.3964484-1-alsi@bang-olufsen.dk/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches