Date: Fri, 8 Oct 2010 19:41:28 +0200
From: David Lamparter <equinox@diac24.net>
To: Ben Greear <greearb@candelatech.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	ath9k <ath9k-devel@venema.h4ckr.net>
Subject: Re: [ath9k-devel] trying to set tx power (using txpower option)
Message-ID: <20101008174128.GC946034@jupiter.n2.diac24.net>
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 <4CAF4B70.9050001@candelatech.com>
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On Fri, Oct 08, 2010 at 10:24:50AM -0700, Ben Greear wrote:
> On 10/08/2010 10:12 AM, Johannes Berg wrote:
> > On Fri, 2010-10-08 at 10:07 -0700, Ben Greear wrote:
> >
> >> Well, the command fails because of this check (mbm is 20 in his case)
> >> cfg.c:
> >> 	case NL80211_TX_POWER_FIXED:
> >> 		if (mbm<  0 || (mbm % 100))
> >> 			return -EOPNOTSUPP;
> >>
> >> That mbm % 100 looks quite strange to me..any idea what that is supposed to
> >> accomplish?
> >
> > There's a later division by 100 to go from mBm to dBm ... I think you
> > want 2000, not 20.
> 
> Well, it's documented in iw to be 'mBm', though I surely wouldn't have known
> what that stood for (nothing useful shows up on google for 'mBm units').

d-B-m is deci-Bel-milliWatt, so a mBm ostensibly is a
milli-Bel-milliWatt...

(yes, the "m" really encodes "mW"...)


-David