From mboxrd@z Thu Jan 1 00:00:00 1970 From: javier@osg.samsung.com (Javier Martinez Canillas) Date: Wed, 2 Sep 2015 09:44:54 +0200 Subject: [PATCHv2] ARM: EXYNOS: reset Little cores when cpu is up In-Reply-To: <55E64559.7000105@samsung.com> References: <1441117023-25478-1-git-send-email-parkch98@gmail.com> <55E63F8F.4020300@samsung.com> <55E64386.3000903@osg.samsung.com> <55E64559.7000105@samsung.com> Message-ID: <55E6A8F6.5020301@osg.samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hello Krzysztof, On 09/02/2015 02:39 AM, Krzysztof Kozlowski wrote: > On 02.09.2015 09:32, Javier Martinez Canillas wrote: >> Hello Krzysztof, >> >> On 09/02/2015 02:15 AM, Krzysztof Kozlowski wrote: >>> On 01.09.2015 23:17, Chanho Park wrote: >>>> The cpu booting of exynos5422 has been still broken since we discussed >>>> it in last year[1]. This patch is inspired from Odroid XU3 >>>> code (Actually, it was from samsung exynos vendor kernel)[2]. This weird >>>> reset code was founded exynos5420 octa cores series SoCs and only >>>> required for the first boot core is the Little core (Cortex A7). >>>> Some of the exynos5420 boards and all of the exynos5422 boards will require >>>> this code. >>>> >>>> There is two ways to check the little core is the first cpu. One is >>>> checking GPG2CON[1] GPIO value and the other is checking the cluster >>>> number of the first cpu. I selected the latter because it's more easier >>>> than the former. >>>> >>>> [1]:http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/350632.html >>>> [2]:https://patchwork.kernel.org/patch/6782891/ >>>> >>>> Cc: Kevin Hilman >>>> Cc: Javier Martinez Canillas >>>> Cc: Krzysztof Kozlowski >>>> Tested-by: Kevin Hilman >>>> Signed-off-by: Chanho Park >>>> --- >>>> Changes from v1: >>>> .kfc to Little (Cortex A7) and eagle to big (Cortex A15) >>>> .append comments about waiting SPARE2 register >>>> >>>> Changes since RFC: >>>> .drop checking soc_is_exynos5800 to extend this codes to >>>> exynos5420/5422 boards. >>>> .kfc cores will be reset only if the cpu0 is kfc core. >>>> .Rebase top of the kukjin's for-next branch >>>> >>>> arch/arm/mach-exynos/mcpm-exynos.c | 25 ++++++++++++++++++++++++- >>>> arch/arm/mach-exynos/regs-pmu.h | 6 ++++++ >>>> 2 files changed, 30 insertions(+), 1 deletion(-) >>> >>> Thanks for updating the patch. Remaining minor nit about comment style >>> (/* on first line) can be fixed while applying. >>> >>> The patch works good, after disabling bL switcher I have 8 cores running: >>> >>> Tested on Odroid XU4: >>> Reviewed-by: Krzysztof Kozlowski >>> Tested-by: Krzysztof Kozlowski >>> >>> It's 4.3 merge window so the patch will go probably to v4.4. >>> >> >> Isn't this material for the v4.3 -rc cycle since it's fixing a bug >> (CPUs not booting)? So I don't think that's necessary to wait for v4.4. > > It is a bug fix but: > 1. Not a fix for regression introduced in current merge window, I thought the -rc cycle was for stabilization and fix not only regressions introduced during the merge window but also long standing issues. > 2. There may be more subtle issues like the one mentioned below, not > found yet (probably no one tested it with all possible configurations), > Right, this is indeed a better reason to wait for v4.4. > so I don't think rushing with the patch to mainline is good idea. > Yes, agreed. > However your comment reminds me about stable. This actually looks like a > candidate for stable. > >> >> But I was expecting another re-spin as from Abhilash's latest comments [0], >> it seems the same workaround is needed in arch/arm/mach-exynos/platsmp.c >> to avoid the CPU's not booting issue when CCI is disabled in DT and the >> MCPM backend is bypassed. >> >> Although I guess that could be also made as a follow up patch. > > Chanho patch fixes only MCPM path. Regular path (platsmp, firmware) is > not affected so I would expect a following patch. > Ok, hopefully the non MCPM path can also be fixed before v4.4. > Best regards, > Krzysztof > >> Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America