From patchwork Thu Apr 17 18:17:03 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geoff Levand X-Patchwork-Id: 4010251 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C0888BFF02 for ; Thu, 17 Apr 2014 18:20:02 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 083932020F for ; Thu, 17 Apr 2014 18:20:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1253420200 for ; Thu, 17 Apr 2014 18:20:01 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WaqsH-0000gD-VT; Thu, 17 Apr 2014 18:17:25 +0000 Received: from merlin.infradead.org ([2001:4978:20e::2]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WaqsF-0000fp-Op for linux-arm-kernel@bombadil.infradead.org; Thu, 17 Apr 2014 18:17:23 +0000 Received: from 107-1-141-74-ip-static.hfc.comcastbusiness.net ([107.1.141.74] helo=[192.168.254.170]) by merlin.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1WaqsE-00027W-8F; Thu, 17 Apr 2014 18:17:22 +0000 Message-ID: <1397758623.30572.53.camel@smoke> Subject: [PATCH] arm64: Fix PSCI part of booting.txt From: Geoff Levand To: Will Deacon Date: Thu, 17 Apr 2014 11:17:03 -0700 X-Mailer: Evolution 3.10.4-0ubuntu1 Mime-Version: 1.0 Cc: Catalin Marinas , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Correct the PSCI booting text to match the requirements of the PSCI spec. Signed-off-by: Geoff Levand --- Hi Will, Based on the PSCI doc (DEN 0022B.b), to use CPU_ON the cpu can only be powered down with CPU_OFF, and it seems from the doc that the code that calls CPU_OFF could be anywhere in memory, since once the CPU_OFF call is made the cpu is powered off and never executes any more instructions from memory. CPU_ON is given an entry_point_address parameter, which would be specific to the code calling CPU_ON. Did I misunderstand something, or should we change this text as below? -Geoff Documentation/arm64/booting.txt | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index beb754e..8f9074f 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -167,13 +167,12 @@ following manner: value, so CPUs must convert the read value to their native endianness before jumping to it. -- CPUs with a "psci" enable method should remain outside of - the kernel (i.e. outside of the regions of memory described to the - kernel in the memory node, or in a reserved area of memory described - to the kernel by a /memreserve/ region in the device tree). The - kernel will issue CPU_ON calls as described in ARM document number ARM - DEN 0022A ("Power State Coordination Interface System Software on ARM - processors") to bring CPUs into the kernel. +- CPUs with a "psci" enable method should use the PSCI CPU control + functions described in ARM document number ARM DEN 0022A or newer + ("Power State Coordination Interface System Software on ARM + processors"). The boot loader must power off these CPU's using the + PSCI CPU_OFF function. The kernel will issue CPU_ON calls to bring + CPUs into the kernel. The device tree should contain a 'psci' node, as described in Documentation/devicetree/bindings/arm/psci.txt.