From patchwork Thu Jan 9 11:11:25 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Looijmans X-Patchwork-Id: 3458941 Return-Path: X-Original-To: patchwork-davinci@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 B98BEC02DC for ; Thu, 9 Jan 2014 11:13:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 072372012E for ; Thu, 9 Jan 2014 11:13:21 +0000 (UTC) Received: from devils.ext.ti.com (devils.ext.ti.com [198.47.26.153]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AE95F20120 for ; Thu, 9 Jan 2014 11:13:13 +0000 (UTC) Received: from dflxv15.itg.ti.com ([128.247.5.124]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id s09BBs4U004666; Thu, 9 Jan 2014 05:11:54 -0600 Received: from DLEE71.ent.ti.com (dlee71.ent.ti.com [157.170.170.114]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id s09BBp9c012262; Thu, 9 Jan 2014 05:11:52 -0600 Received: from dlep32.itg.ti.com (157.170.170.100) by DLEE71.ent.ti.com (157.170.170.114) with Microsoft SMTP Server id 14.2.342.3; Thu, 9 Jan 2014 05:11:50 -0600 Received: from linux.omap.com (dlelxs01.itg.ti.com [157.170.227.31]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id s09BBmiU018359; Thu, 9 Jan 2014 05:11:48 -0600 Received: from linux.omap.com (localhost [127.0.0.1]) by linux.omap.com (Postfix) with ESMTP id C58F680627; Thu, 9 Jan 2014 05:11:48 -0600 (CST) X-Original-To: davinci-linux-open-source@linux.davincidsp.com Delivered-To: davinci-linux-open-source@linux.davincidsp.com Received: from dlelxv84.itg.ti.com (dlelxv84.itg.ti.com [172.17.0.246]) by linux.omap.com (Postfix) with ESMTP id B471680626 for ; Thu, 9 Jan 2014 05:11:47 -0600 (CST) Received: from red.ext.ti.com (red.ext.ti.com [192.94.93.37]) by dlelxv84.itg.ti.com (8.14.3/8.13.8) with ESMTP id s09BBlne018609 for ; Thu, 9 Jan 2014 05:11:47 -0600 Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by red.ext.ti.com (8.13.7/8.13.7) with ESMTP id s09BBk3P009534 for ; Thu, 9 Jan 2014 05:11:46 -0600 Received: from [216.82.253.147:27989] by server-15.bemta-7.messagelabs.com id 62/EE-12957-2F38EC25; Thu, 09 Jan 2014 11:11:46 +0000 X-Env-Sender: mike.looijmans@topic.nl X-Msg-Ref: server-7.tower-165.messagelabs.com!1389265905!16780753!1 X-Originating-IP: [209.17.115.46] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogMjA5LjE3LjExNS40NiA9PiAxMzQ5NA==\n X-StarScan-Received: X-StarScan-Version: 6.9.16; banners=-,-,- X-VirusChecked: Checked Received: (qmail 20570 invoked from network); 9 Jan 2014 11:11:45 -0000 Received: from atl4mhob08.myregisteredsite.com (HELO atl4mhob08.myregisteredsite.com) (209.17.115.46) by server-7.tower-165.messagelabs.com with SMTP; 9 Jan 2014 11:11:45 -0000 Received: from mailpod.hostingplatform.com ([10.30.71.205]) by atl4mhob08.myregisteredsite.com (8.14.4/8.14.4) with ESMTP id s09BBiPa013140 for ; Thu, 9 Jan 2014 06:11:44 -0500 Received: (qmail 27249 invoked by uid 0); 9 Jan 2014 11:11:44 -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; 9 Jan 2014 11:11:44 -0000 From: Mike Looijmans To: Subject: [PATCH] i2c-davinci: Handle signals gracefully Date: Thu, 9 Jan 2014 12:11:25 +0100 Message-ID: <1389265885-26777-1-git-send-email-mike.looijmans@topic.nl> X-Mailer: git-send-email 1.7.9.5 CC: , , , , Mike Looijmans X-BeenThere: davinci-linux-open-source@linux.davincidsp.com X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: Errors-To: davinci-linux-open-source-bounces@linux.davincidsp.com X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham 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 When a signal is caught while the i2c-davinci bus driver is transferring, the drive just "abandons" the transfer and leaves the controller to fend for itself. The next I2C transaction will find the controller in an undefined state and often results in a stream of "initiating i2c bus recovery" messages until the controller arrives in a defined state. This behaviour also sends out "half" or possibly even mixed messages to I2C client devices which may put them in an undesired state as well. This patch fixes this issue by always attempting to finish the current transaction, and then check on a pending signal. It either reports success if all data has been transferred, or it returns failure when the transaction was aborted. This keeps the controller in a defined state, and is also much friendlier towards client devices, because it will only send complete messages. Before this patch, reading an I2C device in a loop and interrupting it often resulted in a "initiating i2c bus recovery" storm and not being able to communicate via I2C for several seconds. With this patch, the userspace call simply returns EINTR and the next I2C transaction succeeds without errors. Signed-off-by: Mike Looijmans --- drivers/i2c/busses/i2c-davinci.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c index 132369f..102673b 100644 --- a/drivers/i2c/busses/i2c-davinci.c +++ b/drivers/i2c/busses/i2c-davinci.c @@ -372,9 +372,9 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) flag |= DAVINCI_I2C_MDR_STP; davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); - r = wait_for_completion_interruptible_timeout(&dev->cmd_complete, + r = wait_for_completion_timeout(&dev->cmd_complete, dev->adapter.timeout); - if (r == 0) { + if (unlikely(r == 0)) { dev_err(dev->dev, "controller timed out\n"); davinci_i2c_recover_bus(dev); i2c_davinci_init(dev); @@ -384,7 +384,6 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) if (dev->buf_len) { /* This should be 0 if all bytes were transferred * or dev->cmd_err denotes an error. - * A signal may have aborted the transfer. */ if (r >= 0) { dev_err(dev->dev, "abnormal termination buf_len=%i\n", @@ -436,22 +435,30 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) ret = i2c_davinci_wait_bus_not_busy(dev, 1); if (ret < 0) { dev_warn(dev->dev, "timeout waiting for bus ready\n"); - return ret; + goto error; } for (i = 0; i < num; i++) { + if (signal_pending(current)) { + dev_dbg(dev->dev, "%s [%d/%d] %#x ERESTARTSYS\n", + __func__, i + 1, num, msgs[i].addr); + ret = -ERESTARTSYS; + goto error; + } ret = i2c_davinci_xfer_msg(adap, &msgs[i], (i == (num - 1))); - dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num, - ret); + dev_dbg(dev->dev, "%s [%d/%d] %#x ret: %d\n", __func__, i + 1, + num, msgs[i].addr, ret); if (ret < 0) - return ret; + goto error; } + ret = num; +error: #ifdef CONFIG_CPU_FREQ complete(&dev->xfr_complete); #endif - return num; + return ret; } static u32 i2c_davinci_func(struct i2c_adapter *adap)