VHT 160Mhz and nss related config.

[Johannes Berg]

On Fri, 2017-02-10 at 14:58 -0800, Ben Greear wrote:
> So, it appears that the ath10k QCA9984 4x4 160Mhz chip can do 4x4
> MIMO at VHT80, but
> it can do only 2x2 MIMO at VHT160/80+80.
> 
> When configuring a peer, we need to tell the firmware the number of
> spatial streams
> of the peer at VHT160 and at VHT80 and lower.  They are not the same
> value.
> 
> I cannot think of any standard way to get this information based on
> VHT capabilities and such.  Currently, one could just assume VHT160
> NSS is 1/2 of the VHT80 NSS, but that is unlikely to be true for all
> vendors.

This was recently added to the VHT capabilities in the spec, see Table
9-250 in 802.11-2016.

johannes