Date: Thu, 11 Dec 2014 14:08:50 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-acpi@freebsd.org Cc: Colin Percival <cperciva@freebsd.org> Subject: Re: ENXIOing non-present battery Message-ID: <201412111408.50866.jhb@freebsd.org> In-Reply-To: <54840781.70603@freebsd.org> References: <54840781.70603@freebsd.org>
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On Sunday, December 07, 2014 2:53:37 am Colin Percival wrote: > Hi ACPI people, > > On my Dell Latitude E7440 laptop, the ACPI reports two batteries: First > the battery which exists; and second, a "Not Present" battery with zeroed > statistics. FreeBSD, not realizing that this second battery is a complete > myth -- the E7440 only has one battery, and there is nowhere to add another > -- faithfully reports the data from ACPI to userland. > > Unfortunately it causes some problems there; in particular, KDE interprets > it as meaning that the system should have two batteries, and when it sees > that the "second" battery has 0% power remaining it kicks off the "battery > is low, turn the laptop off" code. If that code is disabled, it still > displays the wrong battery-charge-remaining status icons. > > For dealing with such broken ACPIs, it seems like not attaching a non-present > battery would be a good idea. This shouldn't be the default behaviour, since > there are plenty of systems where a non-present battery might be inserted at > a later time; but I see nothing wrong with adding an option. > > The attached patch adds a acpi.cmbat.hide_not_present loader tunable which, > as the name suggests, hides non-present batteries; this is done in the probe > code by returning ENXIO if the tunable is set to a nonzero value and > acpi_BatteryIsPresent returns zero. With this patch and the tunable set my > laptop behaves appropriately; and (aside from wasting a few bytes of memory) > there should be no effect on systems where the tunable is not set. > > Any objections to me committing this? Does setting hint.battery.1.disabled=1 work for you? -- John Baldwin
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