Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757668AbaAHVdl (ORCPT ); Wed, 8 Jan 2014 16:33:41 -0500 Received: from mail-vb0-f41.google.com ([209.85.212.41]:57627 "EHLO mail-vb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757243AbaAHVdg (ORCPT ); Wed, 8 Jan 2014 16:33:36 -0500 MIME-Version: 1.0 In-Reply-To: <20140108210228.GO27432@n2100.arm.linux.org.uk> References: <1389187991-26446-1-git-send-email-gautam.vivek@samsung.com> <20140108143529.GB14122@mudshark.cambridge.arm.com> <20140108192028.GM27432@n2100.arm.linux.org.uk> <20140108210228.GO27432@n2100.arm.linux.org.uk> Date: Wed, 8 Jan 2014 13:33:35 -0800 X-Google-Sender-Auth: ZDw4UIrrVKLYcmTHEUGunZXigNw Message-ID: Subject: Re: [PATCH] arm: Add Arm Erratum 773769 for Large data RAM latency. From: Doug Anderson To: Russell King - ARM Linux Cc: Will Deacon , Vivek Gautam , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-samsung-soc@vger.kernel.org" , "kgene.kim@samsung.com" , "sboyd@codeaurora.org" , David Garbett , Catalin Marinas , "gregory.clement@free-electrons.com" , Olof Johansson Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Russell, On Wed, Jan 8, 2014 at 1:02 PM, Russell King - ARM Linux wrote: > On Wed, Jan 08, 2014 at 11:43:29AM -0800, Doug Anderson wrote: >> Olof came up with the idea that you could update the RW firmware >> (affects initial boot) and then cache away the value and restore it in >> the kernel after resume. That would still require a kernel patch but >> perhaps a less objectionable one. ...of course if writing this >> register is a problem in secure mode then maybe that patch would be >> NAKed anyway. > > It's not a problem in secure mode, since secure mode will have access > to the register. It's the non-secure mode where various registers > either ignore writes, or they trigger an exception that are the problem. > > Consider what would happen if an exception were to be triggered when no > exception handlers were installed (eg, because the MMU is not enabled.) OK, good to know. ...so if someone wanted to code up this patch and send upstream they would be able to. :) -Doug -- 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/