From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934032AbbA1CKP (ORCPT ); Tue, 27 Jan 2015 21:10:15 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:41202 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759895AbbA1B2X (ORCPT ); Tue, 27 Jan 2015 20:28:23 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Petazzoni , Andrew Lunn Subject: [PATCH 3.18 33/61] ARM: mvebu: completely disable hardware I/O coherency Date: Tue, 27 Jan 2015 17:26:45 -0800 Message-Id: <20150128012640.523026252@linuxfoundation.org> X-Mailer: git-send-email 2.2.2 In-Reply-To: <20150128012636.936333725@linuxfoundation.org> References: <20150128012636.936333725@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-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: Greg Kroah-Hartman --- arch/arm/mach-mvebu/coherency.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- 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)