From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rich Townsend Subject: Re: General Questions: Date: Fri, 04 Feb 2005 09:47:32 -0500 Message-ID: <42038B04.8070908@bartol.udel.edu> References: <1107520354.4248.16.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <1107520354.4248.16.camel@localhost> Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: jeremy-9vekgGPT+OA7YuNMryXyOw@public.gmane.org, Acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org Jeremy Moles wrote: > Hello again ACPI gurus! Many thanks for the last tip; I was able to > decompile and "fix" the DSDT rather easily using the advice from your > responses. > > I have a few questions about batteries: > > I was looking around the battery driver code last night trying to find > out what the battery "alarm" actually does. Unfortuneately (and I only > spent a few minutes looking), I wasn't able to easily see what the > function of this feature was. I guess my first question is: does it do > anything at all? :) The 'alarm' feature implemented in Linux is actually mapped to the _BTP (battery trip point) of the ACPI specification. Section 10.2.2.4 of this spec indicates that a notify must be issued when the battery remaining capacity crosses this alarm level (either falling below or rising above). When the battery receives this notification, it dispatches a battery event, which shows up in /proc/acpi/events. What action is taken on this event is up to whatever userspace application you are using. I myself have configured acpid so that when a battery event is read, AND the system is on battery power, AND the remaining capacity is below the alarm level, the system automatically suspends (using swsusp2). > > Secondly, would it be beyond of the scope of ACPI for the battery driver > to generate ACPI events when the power gets low? Or is there already > something like this that exists that I'm missing? I tried > watching /proc/acpi/event last as my battery discharged and didn't see > any unusual activity. As per the stuff above, there is already stuff there. However, it only works through the _BTP functionality. If this functionality is not implemented in the DSDT -- or if the alarm level is set crazy low -- then you lose the capability to get advanced warning of low-power situations. > > Thirdly, does the kernel have access to the LED lights on a typical > laptop? That is, does it have the ability to ping the LED and make it > light up? Or, is that something controlled entirely by hardware? It > would be rather neat, I think, to use my "bluetooth" LED (since I don't > have bluetooth) in an arbitrary way. This really depends on the laptop in question. Do you by any chance have an Acer? My Acer TM4502 has an unused bluetooth LED/button, and I think there *might* be a way to control it through the BIOS (see recent posts by Johan Vromans). cheers, Rich ------------------------------------------------------- This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting Tool for open source databases. Create drag-&-drop reports. Save time by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc. Download a FREE copy at http://www.intelliview.com/go/osdn_nl