Return-path: Received: from smtp.rutgers.edu ([128.6.72.243]:44388 "EHLO annwn14.rutgers.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752848AbXDIEqF (ORCPT ); Mon, 9 Apr 2007 00:46:05 -0400 From: Michael Wu To: Larry Finger Subject: Re: [PATCH] mac80211: Report correct wireless statistics Date: Mon, 9 Apr 2007 00:43:29 -0400 Cc: John Linville , Michael Buesch , Bcm43xx-dev@lists.berlios.de, linux-wireless@vger.kernel.org, Jiri Benc References: <461877ea.cyxM3SSnr6WhYkjX%Larry.Finger@lwfinger.net> <200704082031.59934.flamingice@sourmilk.net> <4619B90E.1030403@lwfinger.net> In-Reply-To: <4619B90E.1030403@lwfinger.net> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2034599.ngmQpmyn6N"; protocol="application/pgp-signature"; micalg=pgp-sha1 Message-Id: <200704090043.34436.flamingice@sourmilk.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: --nextPart2034599.ngmQpmyn6N Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Sunday 08 April 2007 23:54, Larry Finger wrote: > Why would I want to do this? Did it fix the output? > If the community agrees on anything, it is=20 > that the signal is given in dBm (i.e. a negative number) and that the rssi > is a positive number. Nope. dBm doesn't have to be negative, though it often is since most wirele= ss=20 hardware isn't that powerful. RSSI is simply a number that's bigger for=20 stronger signals. It could be dBm, but it doesn't have to be. If you want a= =20 stronger definition of RSSI, look at RCPI. > The firmware in the bcm43xx chips return a quantity=20 > that looks like an rssi with a received packet, and > bcm43xx_rssi_postprocess turns that into a quantity that looks like dBm. > Your patch reverses those designations and mixes up the two quantities. > Again I ask "Why"? > Because of the naming/use of the statistics in mac80211 and WE. Signal ends= up=20 getting assigned to (struct iw_quality).qual, which is actually just an=20 arbitrary link quality indicator, not dBm. Anything you care about can be p= ut=20 there. (r)ssi gets assigned to (struct iw_quality).level, which is RSSI. WE= =20 allows that and noise to be specified in either arbitrary units or dBm or=20 RCPI. Yes, I did reverse your conventions, but it makes more sense this way. (R)S= SI=20 is always valid to assign to (struct iw_quality).level and signal ((struct= =20 iw_quality).qual) is quite arbitrary and cannot be specified in specific=20 units. Signal should be probably be renamed to qual to make it more clear that it = is=20 arbitrary. =2DMichael Wu --nextPart2034599.ngmQpmyn6N Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQBGGcR2T3Oqt9AH4aERAnWKAJ4h0xjh03/Z/0sjedXG8qK4pYGuNgCfQE3b bq3gVUtQCox6Rboumr811Ho= =OTBz -----END PGP SIGNATURE----- --nextPart2034599.ngmQpmyn6N-- -: 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