Return-path: Received: from mail-qy0-f181.google.com ([209.85.216.181]:32905 "EHLO mail-qy0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099Ab1JUWCc convert rfc822-to-8bit (ORCPT ); Fri, 21 Oct 2011 18:02:32 -0400 Received: by qyk27 with SMTP id 27so4346952qyk.19 for ; Fri, 21 Oct 2011 15:02:31 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: =?ISO-8859-1?Q?G=E1bor_Stefanik?= Date: Sat, 22 Oct 2011 00:02:11 +0200 Message-ID: (sfid-20111022_000241_407613_8304DCDA) Subject: Re: Setting negative value in dBm for power output (txpower) To: =?ISO-8859-2?Q?Patryk_=AF=F3=B3towski?= Cc: linux-wireless@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2011/10/21 Patryk Żółtowski : > 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? > > and in  e.g. in drivers/net/wireless/iwlwifi/iwl-4965.h  also the min > power output is limited by this define: > >  IWL_TX_POWER_TARGET_POWER_MIN       (0) > > Is it possible to modify source to allow negative power output in dBm > that would work? Or is it physical limitation from the hardware? I'm > doing just a research using Intel Corporation PRO/Wireless 4965 AG > card  and right now I don't require to support other hardware. Is > there any way to check minimum power output capability by given > wireless card? I'm not proficient with driver hacking so any hint > where to start (which file to look up, references) would be helpful. > > Thanks, > Patryk > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at  http://vger.kernel.org/majordomo-info.html > -- Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)