Message-ID: <1452090998.2541.18.camel@sipsolutions.net> (sfid-20160106_153644_478475_2DBF2BBE)
Subject: Re: [RFC 1/2] nl80211: add extended feature for BSS selection
 support
From: Johannes Berg <johannes@sipsolutions.net>
To: Arend van Spriel <arend@broadcom.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>
Date: Wed, 06 Jan 2016 15:36:38 +0100
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On Wed, 2016-01-06 at 11:16 +0100, Arend van Spriel wrote:

> So do we want want a dedicated "bss selection capability" flag iso 
> extended feature in which the driver can indicate the supported 
> selection criteria to user-space? Guess so.

Frankly, I'm not really quite sure.

The alternative is to just treat all of this as advisory and not worry,
so that userspace can specify all it wants and the driver will use all
it can.

That seems mostly reasonable as well.

> I played a trick in reusing ATTR_BSS_SELECT_BAND_PREF. When 
> ATTR_BSS_SELECT_RSSI_ADJUST is passed the ATTR_BSS_SELECT_BAND_PREF
> is 
> used to determine in which band the rssi is adjusted. So "band" and 
> "rssi_adjust" are mutual exclusive.

Yeah, OK, I think that might have confused me a bit :)

> > But logically - does it even make sense? If you already prefer that
> > band, why give it a boost still? Just disable RSSI? Hmm.
> 
> I hope the use-cases mentioned clarify this.
> 

Right. So realistically, writing this a bit more verbosely, you have

1) rssi_preference, band_preference(band)
2) rssi_adjust(band, delta), rssi_preference

and perhaps

3) rssi_preference

as the default?

As for 1), you said it was "band, rssi" but it seems you really meant
the other way around since before you said "band" was a tie-breaker.


Perhaps then, the API should just expose the two "primitives"
 * band_preference(band)
 * rssi_adjust(band, delta)?

johannes