From: Johannes Berg <johannes@sipsolutions.net>
To: "Gábor Stefanik" <netrolller.3d@gmail.com>
Cc: "Patryk Żółtowski" <patryk.zoltowski@gmail.com>,
linux-wireless@vger.kernel.org
Subject: Re: Setting negative value in dBm for power output (txpower)
Date: Sat, 22 Oct 2011 15:30:04 +0200 [thread overview]
Message-ID: <1319290204.3956.0.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <CA+XFjiq6EJNczcotbk3R5YQXa-iY_2FY8KK4UN69XxSTm8LtoQ@mail.gmail.com> (sfid-20111022_000241_407613_8304DCDA)
On Sat, 2011-10-22 at 00:02 +0200, Gábor Stefanik wrote:
> 2011/10/21 Patryk Żółtowski <patryk.zoltowski@gmail.com>:
> > I'm doing a research and I'm wondering if it's possible to hack
> > wireless drivers to allow setting txpower to smaller value than 1mW
> > (e.g. 0.1mW = -10dBM, or even 0.01mW). I've checked source code and in
> > net/mac80211/cfg.c there is the following check:
> >
> > if (mbm < 0 || (mbm % 100))
> > return -EOPNOTSUPP;
>
> The "mbm % 100" part is even weirder; why do we even use millibels if
> we only allow whole-decibel values?
This is really just historic -- nobody has so far cared about TX power
enough to clean up the APIs for it etc. The distinction between
"automatic", "fixed" and "limited" (auto <= some value) is also not
really done very well here.
johannes
next prev parent reply other threads:[~2011-10-22 13:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-21 21:35 Setting negative value in dBm for power output (txpower) Patryk Żółtowski
2011-10-21 22:00 ` wwguy
2011-10-21 22:02 ` Gábor Stefanik
2011-10-22 13:30 ` Johannes Berg [this message]
2011-10-22 1:44 ` Adrian Chadd
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