From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Babic Date: Thu, 09 Jan 2014 12:10:52 +0100 Subject: [U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core In-Reply-To: <20140109062823.GC21717@S2101-09.ap.freescale.net> References: <1389189577-3092-1-git-send-email-festevam@gmail.com> <456edf30a52d41ab9e2dea929c1b74d2@BLUPR03MB309.namprd03.prod.outlook.com> <20140109062823.GC21717@S2101-09.ap.freescale.net> Message-ID: <52CE83BC.2000008@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Shawn, On 09/01/2014 07:28, Shawn Guo wrote: > On Thu, Jan 09, 2014 at 03:50:06AM +0000, Hui.Liu at freescale.com wrote: >> The commit log really get me confused, why we need enable one ERRATA which should not be applied? > > It's been enabled as a workaround for the reboot issue we were seeing > before. But I get reminded that the workaround may not be needed > anymore, because of the recent kernel commit 87a84b69 (ARM: imx: replace > imx6q_restart() with mxc_restart()). The real change is that we do not > call of_iomap() in restart hook now. > > Fabio, > > Can you give it a test to see if reboot works fine with v3.13-rc kernel > with dropping the ERRATA from u-boot? If reboot works and nothing else > breaks, we may want to just remove the ERRATA selection from u-boot. > +1 If the workaround must be set for dual/quad, it is not clear to me if there are some disadvantages to let it enabled for solo. >> This will make customer confused at all. We need find the real root-cause for it other than hack it >> Otherwise, you will get more and more problems sooner or later... > > If you go through the thread [1], you will see that the root-cause had > pretty much been identified, - issuing dmb instructions in a tight loop > causes the problem. But people did not reach a conclusion how it should > be fixed. Exactly, and more frightening IMHO is what can happen is user space if gcc uses dmb. Regards, Stefano -- ===================================================================== DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de =====================================================================