From mboxrd@z Thu Jan 1 00:00:00 1970 From: vojtech@suse.cz (Vojtech Pavlik) Date: Thu, 06 Jul 2006 06:19:30 +0000 Subject: [lm-sensors] Generic interface for accelerometers (AMS, HDAPS, Message-Id: <20060706061930.GA6033@suse.cz> List-Id: References: <44AC5261.9050708@shaw.ca> In-Reply-To: <44AC5261.9050708@shaw.ca> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Robert Hancock Cc: Henrique de Moraes Holschuh , Pavel Machek , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, hdaps-devel@lists.sourceforge.net, Stelian Pop , Michael Hanselmann On Wed, Jul 05, 2006 at 05:59:29PM -0600, Robert Hancock wrote: > Henrique de Moraes Holschuh wrote: > >HDAPS talks to the embedded controller using IO over the LPC bus, and not > >to > >the accelerometer chip or to a simple A/D i2c chip which is used excusively > >for accelerometer access. The EC interface for HDAPS data retrieval is > >not friendly to any errors, and hardlocks the machine somehow if any > >firmware bugs hit or if we violate any of the rules (that are not written > >anywhere) about how to access the EC without geting the SMBIOS unhappy. > > > >So, turning off HDAPS polling while it is not necessary really looks like a > >good idea overall. > > > >We are investigating the ACPI global lock as a way to at least get the > >SMBIOS to stay away from the EC while we talk to it, but we don't know if > >the entire SMBIOS firmware respects that lock. > > It had better, that is exactly what the ACPI Global Lock is supposed to > prevent (concurrent access to non-sharable resources between the OS and > SMI code). The ACPI DSDT contains information on whether or not the > machine requires the Global Lock in order to access the EC or whether it > is safe to access without locking. Isn't that vaild only if you actully use ACPI to access the EC? (AFAIK the HDAPS driver does direct port access.) -- Vojtech Pavlik Director SuSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030186AbWGFGUD (ORCPT ); Thu, 6 Jul 2006 02:20:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030195AbWGFGUB (ORCPT ); Thu, 6 Jul 2006 02:20:01 -0400 Received: from styx.suse.cz ([82.119.242.94]:54987 "EHLO mail.suse.cz") by vger.kernel.org with ESMTP id S1030186AbWGFGUB (ORCPT ); Thu, 6 Jul 2006 02:20:01 -0400 Date: Thu, 6 Jul 2006 08:19:30 +0200 From: Vojtech Pavlik To: Robert Hancock Cc: Henrique de Moraes Holschuh , Pavel Machek , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, hdaps-devel@lists.sourceforge.net, Stelian Pop , Michael Hanselmann Subject: Re: Generic interface for accelerometers (AMS, HDAPS, ...) Message-ID: <20060706061930.GA6033@suse.cz> References: <44AC5261.9050708@shaw.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44AC5261.9050708@shaw.ca> X-Bounce-Cookie: It's a lemon tree, dear Watson! User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 05, 2006 at 05:59:29PM -0600, Robert Hancock wrote: > Henrique de Moraes Holschuh wrote: > >HDAPS talks to the embedded controller using IO over the LPC bus, and not > >to > >the accelerometer chip or to a simple A/D i2c chip which is used excusively > >for accelerometer access. The EC interface for HDAPS data retrieval is > >not friendly to any errors, and hardlocks the machine somehow if any > >firmware bugs hit or if we violate any of the rules (that are not written > >anywhere) about how to access the EC without geting the SMBIOS unhappy. > > > >So, turning off HDAPS polling while it is not necessary really looks like a > >good idea overall. > > > >We are investigating the ACPI global lock as a way to at least get the > >SMBIOS to stay away from the EC while we talk to it, but we don't know if > >the entire SMBIOS firmware respects that lock. > > It had better, that is exactly what the ACPI Global Lock is supposed to > prevent (concurrent access to non-sharable resources between the OS and > SMI code). The ACPI DSDT contains information on whether or not the > machine requires the Global Lock in order to access the EC or whether it > is safe to access without locking. Isn't that vaild only if you actully use ACPI to access the EC? (AFAIK the HDAPS driver does direct port access.) -- Vojtech Pavlik Director SuSE Labs