From patchwork Fri Feb 6 12:00:12 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 437243 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id DB4AE1401DD; Fri, 6 Feb 2015 23:07:36 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YJhh6-00055p-V9; Fri, 06 Feb 2015 12:07:32 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YJhbb-0001ar-3h for kernel-team@lists.ubuntu.com; Fri, 06 Feb 2015 12:01:51 +0000 Received: from av-217-129-142-138.netvisao.pt ([217.129.142.138] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1YJhba-0002jC-L8; Fri, 06 Feb 2015 12:01:50 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.16.y-ckt 034/135] ARM: mvebu: completely disable hardware I/O coherency Date: Fri, 6 Feb 2015 12:00:12 +0000 Message-Id: <1423224113-10958-35-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> References: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Cc: Thomas Petazzoni , Andrew Lunn X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.16.7-ckt6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Petazzoni commit 8f1e8ee28660018a935c7576b9af8ffe1feab54c upstream. The current hardware I/O coherency is known to cause problems with DMA coherent buffers, as it still requires explicit I/O synchronization barriers, which is not compatible with the semantics expected by the Linux DMA coherent buffers API. So, in order to have enough time to validate a new solution based on automatic I/O synchronization barriers, this commit disables hardware I/O coherency entirely. Future patches will re-enable it. Signed-off-by: Thomas Petazzoni Signed-off-by: Andrew Lunn Signed-off-by: Luis Henriques --- arch/arm/mach-mvebu/coherency.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c index c31f4c00b1fc..1163a3e9accd 100644 --- a/arch/arm/mach-mvebu/coherency.c +++ b/arch/arm/mach-mvebu/coherency.c @@ -398,9 +398,14 @@ static int coherency_type(void) return type; } +/* + * As a precaution, we currently completely disable hardware I/O + * coherency, until enough testing is done with automatic I/O + * synchronization barriers to validate that it is a proper solution. + */ int coherency_available(void) { - return coherency_type() != COHERENCY_FABRIC_TYPE_NONE; + return false; } int __init coherency_init(void)