From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: exynos5422-odroid-xu3: MCPM: only 6 of 8 CPUs coming online Date: Fri, 24 Oct 2014 09:00:40 -0700 Message-ID: <7hk33p8nkn.fsf@deeprootsystems.com> References: <7133556.456161412823997169.JavaMail.weblogic@epml02> <7hzjd4lxc5.fsf@deeprootsystems.com> <54485433.2040008@samsung.com> <54485730.10803@samsung.com> <54485B99.2000703@samsung.com> <54485E99.9020004@samsung.com> <54485FDA.8070508@samsung.com> <7hfveeaifs.fsf@deeprootsystems.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mail-pa0-f41.google.com ([209.85.220.41]:61231 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756100AbaJXQAp (ORCPT ); Fri, 24 Oct 2014 12:00:45 -0400 Received: by mail-pa0-f41.google.com with SMTP id rd3so1395826pab.0 for ; Fri, 24 Oct 2014 09:00:44 -0700 (PDT) In-Reply-To: (Abhilash Kesavan's message of "Fri, 24 Oct 2014 20:03:23 +0530") Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Abhilash Kesavan Cc: Abhijeet Dev , Joonyoung Shim , Mauro Ribeiro , linux-samsung-soc , Chander Kashyap , Mauro Ribeiro , Kukjin Kim Abhilash Kesavan writes: > On Thu, Oct 23, 2014 at 9:26 PM, Kevin Hilman wrote: >> Abhilash Kesavan writes: >> >>> The change was based on my reading of the platsmp file of the >>> Odroid-xu3 3.10 kernel and issues experienced previously. From what I >>> understand, the platsmp code in 3.10 kernel is trying to reset the A7s >>> and my change just bypasses the check (no magic here ). The change was >>> only suggested as a workaround to get 8 cores up using MCPM and not an >>> actual fix. I had explained this in my mail to Kevin. So, if this >>> were to be mainlined we would probably need to use something like >>> exynos_core_restart in mcpm along with the workaround. But, this is >>> all guesswork on my part and someone with knowledge of the 3.10 >>> kernel/bootloader needs to comment. >> >> Unfortunately, the harkernel tree git repo doesn't help understand where >> the change came from because an entire v3.10.y based Samsung BSP is >> checked into the tree on top of a v3.8.y kernel in a single commit !!! >> >> Abhilash, in the absence of the original author, could write up a patch >> with your change? >> >> Or, if you can help me with a detailed changelog, I can work on the patch. >> I don't have any exynos docs, so it would be good to have a description >> of what reading/writing to that register are actually doing. > > I could post a patch with an explanation of how I think the workaround > works, but there are a few issues: > - I am not completely confident that this is the best/right change. Maybe post as RFC. > - We are adding code to the exynos mcpm back-end to work-around a > bootloader setting for Odroid-xu3. We would have to make it specific > to odroid somehow as we do not require it for 5420/5800 chromebooks. Hmm, if you have an idea how/where to fix it in u-boot, I'd be glad to give that a try. I'm using the hardkernel u-boot repo: https://github.com/hardkernel/u-boot.git, branch odroidxu3-v2012.07, and would be happy to test any fixes there. > - This might solve the 8 core boot-up issue but other scenarios might > still fail like the one Joonyoung has already reported. I replied yesterday to that report, and the one Joonyoung reported exists with or without your proposed fix, so I don't think they're directly related. >> >> Also, can you explain what you meant by using exynos_core_restart? I >> don't see that function in mainline. > > It is present in linux-next and kgene's for-next branch as part of > this commit "ARM: EXYNOS: SWRESET is needed to boot secondary CPU on > exynos3250". OK, I see it now. Kevin