Re: [PATCH] mac80211: tell drivers the user TX power restriction

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2015-01-21 at 18:54 +0100, Arend van Spriel wrote:

> Okay. Let's forget about the configurable thing. Reading the commit 
> message and I concluded that before the patch it was 'txpwr_limit = 
> min(user, regulatory, ap_11h)'. So for drivers using this value this now 
> changes to 'txpwr_limit = user', right? For those drivers it might be 
> good to have the min() operation added so their behaviour is effectively 
> unchanged by this patch.

The behaviour stays the same for all existing drivers, but drivers now
get a choice between having the min() value (in the existing
bss_conf.txpower) or using the user-specified power (if they do the
min() of the channel themselves) in bss_conf.user_txpower.

So no - it doesn't change the behaviour, it just gives driver authors
more options, and this is needed like I mentioned before - for hw scan
for example you don't want to limit to the *current* channel (the
"regulatory" in the min()) but to the *scan* channel - which only the
device can do since it does the scanning.

johannes