From patchwork Mon Mar 10 11:12:34 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Looijmans X-Patchwork-Id: 328532 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 0C8962C0694 for ; Mon, 10 Mar 2014 22:13:17 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752190AbaCJLNE (ORCPT ); Mon, 10 Mar 2014 07:13:04 -0400 Received: from atl4mhfb03.myregisteredsite.com ([209.17.115.61]:44744 "EHLO atl4mhfb03.myregisteredsite.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752679AbaCJLMy (ORCPT ); Mon, 10 Mar 2014 07:12:54 -0400 Received: from atl4mhob10.myregisteredsite.com (atl4mhob10.myregisteredsite.com [209.17.115.48]) by atl4mhfb03.myregisteredsite.com (8.14.4/8.14.4) with ESMTP id s2ABCqoN009433 for ; Mon, 10 Mar 2014 07:12:52 -0400 Received: from mailpod.hostingplatform.com ([10.30.71.208]) by atl4mhob10.myregisteredsite.com (8.14.4/8.14.4) with ESMTP id s2ABCeKR022353 for ; Mon, 10 Mar 2014 07:12:40 -0400 Received: (qmail 31429 invoked by uid 0); 10 Mar 2014 11:12:40 -0000 X-TCPREMOTEIP: 88.159.208.100 X-Authenticated-UID: mike@milosoftware.com Received: from unknown (HELO paradigit.TOPIC.LOCAL) (mike@milosoftware.com@88.159.208.100) by 0 with ESMTPA; 10 Mar 2014 11:12:40 -0000 From: Mike Looijmans To: git@xilinx.com, wsa@the-dreams.de, linux-i2c@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mike Looijmans Subject: [PATCH] i2c-cadence: Do not let signals interrupt I2C transfers Date: Mon, 10 Mar 2014 12:12:34 +0100 Message-Id: <1394449954-10797-1-git-send-email-mike.looijmans@topic.nl> X-Mailer: git-send-email 1.7.9.5 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Pressing CTRL-C while communicating with an I2C device leads to erratic behaviour. The cause is that the controller will interrupt the I2C transfer in progress, and leave the client device in an undefined state. Many drivers do not handle error return codes on I2C transfers. The calling driver has no way of telling how much of the transfer has actually completed, so it cannot reliably determine the device's state. The best solution here is to not handle signals in the I2C bus driver at all, but always complete a transaction before returning control. See for a related patch and discussion on this topic: http://lkml.org/lkml/2014/1/9/246 Acked-by: Soren Brinkmann --- drivers/i2c/busses/i2c-cadence.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c index 86713d6..32ce2ee 100644 --- a/drivers/i2c/busses/i2c-cadence.c +++ b/drivers/i2c/busses/i2c-cadence.c @@ -452,16 +452,12 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg, cdns_i2c_msend(id); /* Wait for the signal of completion */ - ret = wait_for_completion_interruptible_timeout( - &id->xfer_done, HZ); - if (ret < 1) { + ret = wait_for_completion_timeout(&id->xfer_done, HZ); + if (ret == 0) { cdns_i2c_master_reset(adap); - if (!ret) { - dev_err(id->adap.dev.parent, + dev_err(id->adap.dev.parent, "timeout waiting on completion\n"); - return -ETIMEDOUT; - } - return ret; + return -ETIMEDOUT; } cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);