From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Airlie Subject: Re: [PATCH][ACPI] AC/DC notifier Date: Wed, 7 Oct 2009 18:16:29 +1000 Message-ID: <21d7e9970910070116h6cf4e472i309537e9b4bb1e08@mail.gmail.com> References: <20090812005532.GA31003@srcf.ucam.org> <20090814163233.GC1626@ucw.cz> <20090816074008.GA11624@1wt.eu> <4ACB59E2.3000600@amd.com> <20091007073121.GA31245@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <20091007073121.GA31245@elf.ucw.cz> Sender: linux-kernel-owner@vger.kernel.org To: Pavel Machek Cc: "Tippett, Matthew" , Willy Tarreau , Matthew Garrett , "Langsdorf, Mark" , lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, "Li, Samuel" List-Id: linux-acpi@vger.kernel.org On Wed, Oct 7, 2009 at 5:31 PM, Pavel Machek wrote: > On Tue 2009-10-06 10:53:22, Tippett, Matthew wrote: >> (Resending as text-only - sorry) >> >> Bringing this item back up again. >> >> I am not suggesting that the application of any particular policy >> appears within the kernel or userspace or a secondary policy engine. >> In general I am also against codifying policy within drivers. >> >> I am interested seeing the ACPI notifier mechanism expanded to allow >> AC/DC state changes propagate to other kernel drivers without requiring >> a userspace in between. >> >> I can continue to come up with real scenarios that would possibly >> require kernel-to-kernel notification, but would rather focus this >> discussion of the pure technical issues associated with adding the >> notifier to the AC/DC ACPI subsystem. > > Please do. So far you did not show valid use for such notifier. > > (Ok, I know of one. Old amd64 notebooks had cpufreq scaling enabled, > with battery unable to supply enough current to feed the CPU at > highest cpufreq setting. At that point, scaling cpufreq down at unplug > is correctness issue, and AC/DC notifier in kernel makes > sense.) > > So... what do you want to use it for? I'm not sure we have a open driver use case for this, if not I suggest we remove it and only add it when a user is added to the kernel. Dave.