From patchwork Thu Jun 6 13:43:35 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Ruppert X-Patchwork-Id: 249423 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 251802C0098 for ; Thu, 6 Jun 2013 23:44:10 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751322Ab3FFNoI (ORCPT ); Thu, 6 Jun 2013 09:44:08 -0400 Received: from mail.abilis.ch ([195.70.19.74]:27312 "EHLO mail.abilis.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078Ab3FFNoH (ORCPT ); Thu, 6 Jun 2013 09:44:07 -0400 Received: from vzimbra0.lan (vzimbra0.lan [10.41.22.42]) by mail.abilis.ch (8.13.8/8.13.8) with ESMTP id r56DhcPv025968; Thu, 6 Jun 2013 15:43:38 +0200 Received: from ab42.lan (ab42.lan [10.41.22.170]) by vzimbra0.lan (Postfix) with ESMTP id F36EA901017; Thu, 6 Jun 2013 15:43:37 +0200 (CEST) Received: by ab42.lan (Postfix, from userid 2100) id EBA3A15C2; Thu, 6 Jun 2013 15:43:37 +0200 (CEST) From: Christian Ruppert To: Wolfram Sang , Mika Westerberg Cc: Jean Delvare , Pierrick Hascoet , Christian Ruppert , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] i2c: designware: fix race between subsequent xfers Date: Thu, 6 Jun 2013 15:43:35 +0200 Message-Id: <1370526216-10060-1-git-send-email-christian.ruppert@abilis.com> X-Mailer: git-send-email 1.7.1 X-Spam-Status: No, score=-1.5 required=5.0 tests=ALL_TRUSTED,BAYES_05 autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on dmmail0.lan Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org The designware block is not always properly disabled in the case of transfer errors. Interrupts from aborted transfers might be handled after the data structures for the following transfer are initialised but before the hardware is set up. This might corrupt the data structures to the point that the system is stuck in an infinite interrupt loop (where FIFOs are never emptied). This patch cleanly disables the designware-i2c hardware at the end of every transfer, successful or not. Signed-off-by: Christian Ruppert --- drivers/i2c/busses/i2c-designware-core.c | 14 +++++++++++--- 1 files changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 6c0e776..65c0c7a 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -588,10 +588,20 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, HZ); if (ret == 0) { dev_err(dev->dev, "controller timed out\n"); + /* i2c_dw_init implicitly disables the adapter */ i2c_dw_init(dev); ret = -ETIMEDOUT; goto done; - } else if (ret < 0) + } + + /* + * We must disable the adapter before unlocking the &dev->lock mutex + * below. Otherwise the hardware might continue generating interrupts + * which in turn causes a race condition with the following transfer. + */ + __i2c_dw_enable(dev, false); + + if (ret < 0) goto done; if (dev->msg_err) { @@ -601,8 +611,6 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) /* no error */ if (likely(!dev->cmd_err)) { - /* Disable the adapter */ - __i2c_dw_enable(dev, false); ret = num; goto done; }