From mboxrd@z Thu Jan 1 00:00:00 1970 From: jan.kiszka@web.de (Jan Kiszka) Date: Mon, 10 Nov 2014 09:25:15 +0100 Subject: AMR: sun7i: CPU hotplug support? In-Reply-To: <5460554A.1060701@web.de> References: <545FC215.7010802@web.de> <20141109231744.GC2989@lukather> <5460554A.1060701@web.de> Message-ID: <5460766B.8070000@web.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2014-11-10 07:03, Jan Kiszka wrote: > On 2014-11-10 00:17, Maxime Ripard wrote: >> Hi Jan, >> >> On Sun, Nov 09, 2014 at 08:35:49PM +0100, Jan Kiszka wrote: >>> did anyone already happen to look into enabling CPU hotplug for the >>> Allwinner A20 in upstream? I'm currently running the sunxi-next branch >>> on Banana Pi, and echo 0 > .../cpu1/online just hangs the system. The >>> old 3.4 LeMaker kernel works fine in this regard. I can try to look into >>> details and port things over, just want to avoid duplicate efforts. >> >> Having hotplug support would indeed be very welcome. >> >> However, it should be done in u-boot, through PSCI, and not in the >> kernel itself. >> >> As far as I'm aware, no one worked actively on it, beside some WIP >> commit from Marc a while ago: >> https://git.kernel.org/cgit/linux/kernel/git/maz/u-boot.git/commit/?h=wip/psci&id=45379c0f9cf812f0f62722f4015ec907fa5dc144 > > OK - I guess I will need a little guidance in then: Is there a good > reference board to study and to derive from? And maybe also: What is > missing or not working in that u-boot branch? If I get this interface > right, I just takes some device tree bits to enable this for the kernel > afterward, correct? Started to play with that patch in naive ways: CPU0 locks up when offlining CPU1 - unless I disable the FIQ signal from CPU1. Then it "works", both offlining and onlining again. However, I suspect that this only parks CPU1 in wfi and does not do anything interesting to it. Jan -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: OpenPGP digital signature URL: