Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932972AbaFIWir (ORCPT ); Mon, 9 Jun 2014 18:38:47 -0400 Received: from service87.mimecast.com ([91.220.42.44]:41258 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932999AbaFIWig convert rfc822-to-8bit (ORCPT ); Mon, 9 Jun 2014 18:38:36 -0400 Date: Mon, 9 Jun 2014 23:38:31 +0100 From: Lorenzo Pieralisi To: Doug Anderson Cc: Kukjin Kim , Nicolas Pitre , Abhilash Kesavan , Andrew Bresticker , Inderpal Singh , Thomas Abraham , "olof@lixom.net" , Tushar Behera , Kevin Hilman , Javier Martinez Canillas , "linux-samsung-soc@vger.kernel.org" , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start Message-ID: <20140609223831.GB16889@e102568-lin.cambridge.arm.com> References: <1402090985-8061-1-git-send-email-dianders@chromium.org> <20140607181221.GB25068@e102568-lin.cambridge.arm.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginalArrivalTime: 09 Jun 2014 22:38:27.0333 (UTC) FILETIME=[87C90350:01CF8433] X-MC-Unique: 114060923383400901 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 09, 2014 at 06:03:31PM +0100, Doug Anderson wrote: [...] > Cold boot and resume from suspend are detected via various special > flags in various special locations. Resume from suspend looks at > INFORM1 (0x10048004) for flags. This register is 0 during a cold boot > and has special values set by the kernel at resume time. > > It also looks as if some code looks at 0x10040900 (PMU_SPARE0) to help > tell initial cold boot and secondary CPU bringup. Ok, thanks a lot. It looks like firmware paths should be ready to detect cold vs warm boot, and hopefully do not rely on a specific MPIDR to come up first out of power states. > > I am asking to check if on this platform CPUidle (where the notion of > > primary CPU disappears) has a chance to run properly. > > I believe it should be possible, but we don't have CPUidle implemented > in our current system. Abhilash may be able to comment more. I am interested in more insights, that's very helpful thanks. > > Probably CPUidle won't attain idle states where IRAM content is lost, but I > > am still worried about the primary vs secondaries firmware boot behaviour. > > I don't think iRAM can be turned off for CPUidle. It might be added a system state but I doubt that too and if you are relying on registers for jump addresses that's not even a problem in the first place. > > What happens on reboot from suspend to RAM (or to put it differently, > > what does secure firmware do on reboot from suspend to RAM - in > > particular how is the "jump" address to bootloader/kernel set ?) > > Should be described above now. Thank you very much. Lorenzo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/