From mboxrd@z Thu Jan  1 00:00:00 1970
From: Luis R. Rodriguez <lrodriguez@atheros.com>
Date: Mon, 9 Feb 2009 18:25:14 -0800
Subject: [ath9k-devel] Transmit power control using ath9k
In-Reply-To: <20090210015755.GB4386@tesla>
References: <604f6e750902090738n47e3eb65y62a6e9ce5e883adf@mail.gmail.com>
	<20090210015755.GB4386@tesla>
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On Mon, Feb 09, 2009 at 05:57:55PM -0800, Luis Rodriguez wrote:
> On Mon, Feb 09, 2009 at 07:38:51AM -0800, Kishore Ramachandran wrote:
> > Greetings,
> >
> > I have an AR9160-based 11n miniPCI card, and was wondering if the card and ath9k support transmit power control?
> 
> You mean the ability to change desired TX power?
> 
> If so then yes, we support that by mac80211, and mac80211 then tells us. This
> is handled in mac80211 through the ieee80211_ops:
> 
> struct ieee80211_ops ath9k_ops = {
>         .tx                 = ath9k_tx,
>         .start              = ath9k_start,
>         .stop               = ath9k_stop,
>         .add_interface      = ath9k_add_interface,
>         .remove_interface   = ath9k_remove_interface,
>         .config             = ath9k_config,
>         .config_interface   = ath9k_config_interface,
>         .configure_filter   = ath9k_configure_filter,
>         .sta_notify         = ath9k_sta_notify,
>         .conf_tx            = ath9k_conf_tx,
>         .bss_info_changed   = ath9k_bss_info_changed,
>         .set_key            = ath9k_set_key,
>         .get_tsf            = ath9k_get_tsf,
>         .set_tsf            = ath9k_set_tsf,
>         .reset_tsf          = ath9k_reset_tsf,
>         .ampdu_action       = ath9k_ampdu_action,
> };
> 
> In the TX power case this is handled in ath9k_config():
> 
> -----------------------------------------------------------------
>         if (changed & IEEE80211_CONF_CHANGE_POWER)
>                 sc->sc_config.txpowlimit = 2 * conf->power_level;
> -----------------------------------------------------------------
> 
> Now, currently the way mac80211 receives this from userspace is through
> the old wireless-extensions SIOCSIWTXPOW ioctl. mac80211 implements this via
> ieee80211_ioctl_siwtxpower().
> 
> > If they do, is it on a fine-grained level (e.g. per-packet change allowed)?
> 
> As you can see from above, this is not a question for ath9k but for mac80211,
> as mac80211 just informs us when the tx power has to be changed. The answer
> to the question "does mac80211 supports changing TX power dynamically for each
> packet" is yes, we do that by allowing userspace to pass desired tweaking through
> a radiotap header. In fact not only is TX power supported but other fields such
> as rate.
> 
> For further details check out:
> 
> Documentation/networking/mac80211-injection.txt
> 
> I just had to review that today. The only oudated information there is the URL
> to packetspammer, which I have a correct URL for you today:
> 
> http://git.warmcat.com/cgi-bin/cgit.cgi?url=packetspammer.git/
> 
> The actual git URL is:
> 
> git://git.warmcat.com/packetspammer.git/
> 
> > Also, am guessing that setting/getting the value of this parameter via the iw tool would be useful?
> 
> Sure, so that means through nl80211, that would be welcomed, as
> well as setting the rate. Let me know if you have any other questions.

BTW I don't see any documentation for packetspammer so I have started it:

http://wireless.kernel.org/en/users/Documentation/packetspammer

Please feel free to help elaborate it.

  Luis