From mboxrd@z Thu Jan 1 00:00:00 1970 From: hancockr@shaw.ca (Robert Hancock) Date: Fri, 07 Jul 2006 05:28:55 +0000 Subject: [lm-sensors] Generic interface for accelerometers (AMS, HDAPS, Message-Id: <44ADF117.2060900@shaw.ca> List-Id: References: <44AC5261.9050708@shaw.ca> <20060706061930.GA6033@suse.cz> <20060707024603.GC22666@khazad-dum.debian.net> In-Reply-To: <20060707024603.GC22666@khazad-dum.debian.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Henrique de Moraes Holschuh Cc: Vojtech Pavlik , Pavel Machek , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, hdaps-devel@lists.sourceforge.net, Stelian Pop , Michael Hanselmann Henrique de Moraes Holschuh wrote: > On Thu, 06 Jul 2006, Vojtech Pavlik wrote: >>>> 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.) > > It better be valid for any OS-side access to the EC, otherwise the ACPI > global lock would be utterly useless. The system vendor would have done its > own "global-lock-like" functionality without the need for an ACPI global > lock specification. > > What is not clear to me is whether an ACPI DSDT method is on the "OS side" > or on the "SMM side" of the ACPI global lock. That would be on the OS side of the global lock.. However the OS still needs to maintain its own synchronization between its accesses to the controller, the global lock is not intended for that purpose. It doesn't sound like the HDAPS driver and the ACPI code are necessarily synchronizing their accesses (though I can't say I've looked at the code). -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr at nospamshaw.ca Home Page: http://www.roberthancock.com/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751187AbWGGF3l (ORCPT ); Fri, 7 Jul 2006 01:29:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751186AbWGGF3l (ORCPT ); Fri, 7 Jul 2006 01:29:41 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:12003 "EHLO pd2mo2so.prod.shaw.ca") by vger.kernel.org with ESMTP id S1751185AbWGGF3k (ORCPT ); Fri, 7 Jul 2006 01:29:40 -0400 Date: Thu, 06 Jul 2006 23:28:55 -0600 From: Robert Hancock Subject: Re: Generic interface for accelerometers (AMS, HDAPS, ...) In-reply-to: <20060707024603.GC22666@khazad-dum.debian.net> To: Henrique de Moraes Holschuh Cc: Vojtech Pavlik , Pavel Machek , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, hdaps-devel@lists.sourceforge.net, Stelian Pop , Michael Hanselmann Message-id: <44ADF117.2060900@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <44AC5261.9050708@shaw.ca> <20060706061930.GA6033@suse.cz> <20060707024603.GC22666@khazad-dum.debian.net> User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Henrique de Moraes Holschuh wrote: > On Thu, 06 Jul 2006, Vojtech Pavlik wrote: >>>> 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.) > > It better be valid for any OS-side access to the EC, otherwise the ACPI > global lock would be utterly useless. The system vendor would have done its > own "global-lock-like" functionality without the need for an ACPI global > lock specification. > > What is not clear to me is whether an ACPI DSDT method is on the "OS side" > or on the "SMM side" of the ACPI global lock. That would be on the OS side of the global lock.. However the OS still needs to maintain its own synchronization between its accesses to the controller, the global lock is not intended for that purpose. It doesn't sound like the HDAPS driver and the ACPI code are necessarily synchronizing their accesses (though I can't say I've looked at the code). -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/