From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 30 Nov 2010 14:05:38 -0000 Subject: [PATCH][ ARM cpu hotplug 1/2 ] extract common code for arm cpu hotplug In-Reply-To: <20101130115148.GB31054@n2100.arm.linux.org.uk> References: <20101129104149.GA10703@n2100.arm.linux.org.uk> <20101129192407.GA20761@n2100.arm.linux.org.uk> <20101130110331.GA31054@n2100.arm.linux.org.uk> <20101130115148.GB31054@n2100.arm.linux.org.uk> Message-ID: <004701cb9097$ab173f40$0145bdc0$@deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Russell, > On Tue, Nov 30, 2010 at 11:03:31AM +0000, Russell King - ARM Linux wrote: > > I see no point to what is being proposed in this thread. It's _soo_ > > little code that the platforms have to implement that it really is > > not worth the effort. [...] > Note also that most implementations of this get it wrong. Realview > assumes ARMv6 MPcore layout of the auxcontrol register, which is > cut'n'pasted into s5pv310 (ARMv7) and Tegra (ARMv7) without thinking. > The only implementation which has put some thought into it is the > UX500 one, which is extremely simple. > > So, out of the four existing implementations, at least two need fixing > to be different, and I'll bet that they do have some way to power down > the offlined CPUs for greater power savings. I have patches that fix this for RealView and Versatile Express, I posted them to the list in the past (note that these are now out of date): http://lists.infradead.org/pipermail/linux-arm-kernel/2010-September/026160.html I have a newer version here: git://linux-arm.org/linux-2.6-wd.git cpu-hotplug but it relies on the Versatile Express multi-tile patches that I'm posting at the moment. If the hotplug APIs aren't about to change fundamentally, then I'll repost these patches once the multi-tile stuff is accepted. Will