Setting single rate in ath10k broken by "reject/clear user rate mask if not usable"

[Johannes Berg]

On Fri, 2017-10-27 at 13:41 -0700, Ben Greear wrote:

> ath10k ignores the tx rateset pretty much entirely when sending management
> frames, so even if you set the tx rateset to have only VHT MCS 8,
> management frames are still sent with legacy ratesets.

So that's a driver bug.

> My end goal about this part is to be able to configure a single tx rate
> and have that be allowed again, at least with ath10k.
> 
> Maybe a new flag for drivers like ath10k that at least somewhat ignore
> the tx-rateset for management frames, and this flag would allow us to
> bypass the cannot-set-single-rate check?

What? No, I'm not going to put a driver bug into the API like that!

johannes