Re: [ath5k-devel] [PATCH v2 13/20] cfg80211: Add nl80211 antenna configuration

["Luis R. Rodriguez" <lrodriguez@atheros.com>]

>> > that's not very clear. can you give me an example?
>>
>> iw dev wlan0 set_tx_antenna 4
>
> so you want to transmit on antenna 3. if the card has 3 antennas -
> why not?

None of the legacy 802.11 drivers we support have more than 2
antennas, I am also not aware of any.

>> > what if there is a 'legacy' hardware with 3 or more antennas?
>>
>> Like what?
>
> i can't find an actual real world example for that, but it thought it might be
> possible, from what i know from the atheros eeprom which seems to be prepared
> for up to 6 antennas.

That's for 802.11n, I think it'd be much cleaner to treat that
separately. But -- I can think of using an 802.11n device in legacy
mode of operation using specific antennas.... so there's your example
of a valid case for this.

>> > i don't see how "my" API is too complicated, and i think it allows for a
>> > clear configuration of these cases as well.
>> >
>> > your criticism seems to be based on the fact that it's not clear how to
>> > handle 802.11n chainmask + antenna configuration, but this is not what
>> > my patch is concerned about. let's go step by step...
>>
>> No no, that is my fault, I brought that up, I was hoping we could
>> address it but it seems that we can't as I don't have time to think
>> about this further in a unified clean API. But if its just going to be
>> legacy then I don't see why we would use a large bitmap.
>
> i wanted it to be easily extensibe for 802.11n

If we do want to address 802.11n then I say we go back to the drawing
board and really think about how antennas settings work for 802.11n
and consider chainmask settings.

> and possibly 'legacy' with more antennas in the future.

Legacy devices are dead. I don't know anyone in the industry making
them, the 1 stream 802.11n devices are cheaper today, so there is no
point in the market for it.

> if there really are not any pre-N cards with more than
> 2 antennas out there,

Yup, I think this is the case :)

> and we are sure we don't want to support more than 2
> antennas - well, we could save 6 bits... is it really worth it?

You're right, then if you really don't mind lets think 802.11n through
well then.

  Luis