Return-path: Received: from c60.cesmail.net ([216.154.195.49]:37145 "EHLO c60.cesmail.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273AbYKSTNm (ORCPT ); Wed, 19 Nov 2008 14:13:42 -0500 Subject: Re: [PATCH] wireless: sysfs was displaying different values for level and noise than procfs From: Pavel Roskin To: Andrey Borzenkov Cc: linux-wireless@vger.kernel.org In-Reply-To: <200811151831.26403.arvidjaar@mail.ru> References: <200811151831.26403.arvidjaar@mail.ru> Content-Type: text/plain Date: Wed, 19 Nov 2008 14:13:39 -0500 Message-Id: <1227122019.2196.14.camel@dv> (sfid-20081119_201348_225220_15F9403F) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Sat, 2008-11-15 at 18:31 +0300, Andrey Borzenkov wrote: > Subject: [PATCH] wireless: sysfs was displaying different values for level and noise than procfs > From: Andrey Borzenkov > > /proc/net/wireless asjusts display of signal and noise level depending on > whether units are percentage or dBm. Use the same format in sysfs. This > makes it easy to know unit - below zero is dBm, above zero is percent. I've seen received power up to 3 dBm. The AP was using an amplifier (it's specialized hardware), and it's possible that the card on the station side was exaggerating the signal. However, the data we report should not need any guesswork to be interpreted. It may be parsed by userspace software. Receiving 1 mW out of 200 mW is not impossible in some antenna configurations even with consumer devices. > Before: > {pts/1}% cat /sys/class/net/eth1/wireless/level > 203 > {pts/1}% cat /sys/class/net/eth1/wireless/noise > 166 > + return sprintf(buf, format_string, (__s32)iw->field - \ > + ((iw->qual.updated & IW_QUAL_DBM) ? 0x100 : 0)); \ I think non-dBm data should be shown in a special format: "203/255" where 255 is the maximal value, and the dBm data should be shown as numbers: "-48". This way, we encourage use of dBm data by making it easier to parse. -- Regards, Pavel Roskin