From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Tue, 04 Jun 2013 13:33:30 -0600 Subject: [U-Boot] [PATCH] ARM: tegra: only enable SCU on Tegra20 In-Reply-To: <1369347978-31508-1-git-send-email-swarren@wwwdotorg.org> References: <1369347978-31508-1-git-send-email-swarren@wwwdotorg.org> Message-ID: <51AE410A.1030506@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 05/23/2013 04:26 PM, Stephen Warren wrote: > From: Tom Warren > > The non-SPL build of U-Boot on Tegra only runs on a single CPU, and > hence there is no need to enable the SCU when running U-Boot. If an > SMP OS is booted, and it needs the SCU enabled, it will enable the SCU > itself. U-Boot doing so is redundant. > > The one exception is Tegra20, where an enabled SCU is required for some > aspects of PCIe to work correctly. > > Some Tegra SoCs contain CPUs without a software-controlled SCU. In this > case, attempting to turn it on actively causes problems. This is the case > for Tegra114. For example, when running Linux, the first (or at least > some very early) user-space process will trigger the following kernel > message: > > Unhandled fault: imprecise external abort (0x406) at 0x00000000 > > This is typically accompanied by that process receving a fatal signal, > and exiting. Since this process is usually pid 1, this causes total > system boot failure. Tom, is this patch OK? It's a rather critical bug-fix for Tegra114, so I'd like to make sure it gets into the upcoming release. Thanks.