From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750713AbWC2Nj6 (ORCPT ); Wed, 29 Mar 2006 08:39:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750716AbWC2Nj6 (ORCPT ); Wed, 29 Mar 2006 08:39:58 -0500 Received: from smtp-relay.dca.net ([216.158.48.66]:53633 "EHLO smtp-relay.dca.net") by vger.kernel.org with ESMTP id S1750713AbWC2Nj5 (ORCPT ); Wed, 29 Mar 2006 08:39:57 -0500 Date: Wed, 29 Mar 2006 08:38:35 -0500 From: "Mark M. Hoffman" To: Etienne Lorrain Cc: linux-kernel@vger.kernel.org, lm-sensors , Ian Campbell Subject: Re: I2C_PCA_ISA causes boot delays (was re: sis96x compiled in by error: delay of one minute at boot) Message-ID: <20060329133835.GB8309@jupiter.solarsys.private> References: <20060329034510.GA8309@jupiter.solarsys.private> <20060329092628.16392.qmail@web26908.mail.ukl.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060329092628.16392.qmail@web26908.mail.ukl.yahoo.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello Etienne: * Etienne Lorrain [2006-03-29 11:26:28 +0200]: > --- "Mark M. Hoffman" wrote: > > > 885c885 > > > < # CONFIG_I2C_PCA_ISA is not set > > > --- > > > > CONFIG_I2C_PCA_ISA=y > > > > This alone is the cause of the delay. (I have confirmed it by running some > > similar .configs here.) You almost certainly don't own this specialized > > piece of hardware. Worse still, that particular driver has no code to detect > > whether or not the hardware is present. I cc'ed the listed driver author > > (Ian) just in case this might be corrected... but I guess there is no way > > to fix it. > > > > So the delay is (1) an I2C bus driver that is not actually present, trying to > > probe for (2) seven different sensors chip drivers that certainly aren't present > > on the nonexistent bus. Timeouts ensue. > > > > So unless Ian knows a better way to detect that bus driver... the best I can > > advise is to *not* build in those drivers for hardware that you do not have. > > OK, I know the I2C protocol, and I can imagine a hardware board which does > not have a way to detect its own presence - or the presence of its own ISA bus. > What I dislike the most is that, after the driver has taken more than 20 > seconds to probe something it did not find, it did not display anything to > say "either there is a hardware problem, or you should disable me". I repeat just once more: the supported method for identifying hwmon/sensors chips is a Perl script called sensors-detect that is distributed with the lm-sensors package. > Are you sure that there isn't any distribution around trying to insert > _all_ the modules to do hardware detection? No, because that is not supported. All of the major distributions package lm-sensors, and AFAIK they all build hwmon/sensors as modules. They don't insert any of them by default. If a distro was silly enough to blindly insert them all... then it would take forever to boot and nobody would use it. > Note that most I2C driver detect abscence of the hardware in a lot less than > a second: most of the I2C system is fine. Feel free to write a patch for drivers/busses/i2c/i2c-pca-isa.c; I don't have that hardware myself. Otherwise, my final advice is: Patient: It hurts when I do this. Doctor: Don't do that. Regards, -- Mark M. Hoffman mhoffman@lightlink.com