From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Roskin Subject: Re: dBm cutoff at -1dBm is too low Date: Tue, 09 May 2006 00:54:55 -0400 Message-ID: <1147150495.4453.65.camel@dv> References: <1146760665.5294.65.camel@dv> <20060505172818.GA7543@bougret.hpl.hp.com> <1146972732.24434.89.camel@dv> <20060508171711.GA10948@bougret.hpl.hp.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: NetDev Return-path: Received: from fencepost.gnu.org ([199.232.76.164]:33998 "EHLO fencepost.gnu.org") by vger.kernel.org with ESMTP id S1751372AbWEIEzD (ORCPT ); Tue, 9 May 2006 00:55:03 -0400 Received: from proski by fencepost.gnu.org with local (Exim 4.34) id 1FdKFS-0002n5-AN for netdev@vger.kernel.org; Tue, 09 May 2006 00:55:02 -0400 To: jt@hpl.hp.com In-Reply-To: <20060508171711.GA10948@bougret.hpl.hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 2006-05-08 at 10:17 -0700, Jean Tourrilhes wrote: > > But shouldn't you trust the drivers using IW_QUAL_DBM, whether the value > > is positive or negative? > > You can't remove the test, making the rest pointeless. Old > style driver never used the flags, new style driver that don't report > dBm will never use the flags, and there is not way to dinstinguish > both, apart from the 'sign' of the value. I used "new style driver" as synonymous to the driver using IW_QUAL_DBM and "old style driver" as the one that doesn't use IW_QUAL_DBM. I don't think any drivers need to specify both dBm and non-dBm data for the same device. Drivers that give non-dBm data are already well served by wireless tools. They don't need to change. Drivers that give dBm data had to limit the data to avoid its misinterpretation as non-dBm data. Now IW_QUAL_DBM is supposed to free drivers from such checks. But it doesn't deliver its promise, because the data can still be misinterpreted, just is a different way. Namely, a strong signal (0dBm) can be interpreted as an incredibly weak signal (-256dBm). That's what I want to see fixed. One tricky case would be when the driver sets the max signal e.g. to 30 and reports 35 (i.e. a positive value within the "reasonable" dBm range). I would probably prefer to show it as 30/30 rather than 35dBm, but the driver is nuts anyway, and I'm not really concerned about it to write an extra line of code. -- Regards, Pavel Roskin