From patchwork Thu Aug 30 10:40:04 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joakim Tjernlund X-Patchwork-Id: 180814 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [IPv6:::1]) by ozlabs.org (Postfix) with ESMTP id BE7092C0410 for ; Thu, 30 Aug 2012 20:40:39 +1000 (EST) Received: from gw1.transmode.se (gw1.transmode.se [195.58.98.146]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 74AB32C0040 for ; Thu, 30 Aug 2012 20:40:13 +1000 (EST) Received: from mail1.transmode.se (mail1.transmode.se [192.168.201.18]) by gw1.transmode.se (Postfix) with ESMTP id 504AB258139; Thu, 30 Aug 2012 12:40:07 +0200 (CEST) Received: from gentoo-jocke.transmode.se ([172.20.4.10]) by mail1.transmode.se (Lotus Domino Release 8.5.3FP1) with ESMTP id 2012083012400702-5489 ; Thu, 30 Aug 2012 12:40:07 +0200 Received: from gentoo-jocke.transmode.se (localhost [127.0.0.1]) by gentoo-jocke.transmode.se (8.14.4/8.14.4) with ESMTP id q7UAe7Sn019272; Thu, 30 Aug 2012 12:40:07 +0200 Received: (from jocke@localhost) by gentoo-jocke.transmode.se (8.14.4/8.14.4/Submit) id q7UAe627019271; Thu, 30 Aug 2012 12:40:06 +0200 From: Joakim Tjernlund To: linux-i2c@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH] i2c-mpc: Wait for STOP to hit the bus Date: Thu, 30 Aug 2012 12:40:04 +0200 Message-Id: <1346323204-19210-1-git-send-email-Joakim.Tjernlund@transmode.se> X-Mailer: git-send-email 1.7.8.6 X-MIMETrack: Itemize by SMTP Server on mail1/Transmode(Release 8.5.3FP1|March 07, 2012) at 30/08/2012 12:40:07, Serialize by Router on mail1/Transmode(Release 8.5.3FP1|March 07, 2012) at 30/08/2012 12:40:07, Serialize complete at 30/08/2012 12:40:07 X-TNEFEvaluated: 1 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" mpc_i2c_stop() only initiates STOP but does not wait for it to hit the I2C bus. This is a problem when using I2C devices which uses fairly long clock stretching just before STOP if you also have an i2c-mux which may switch to another bus before STOP has been processed. Signed-off-by: Joakim Tjernlund --- drivers/i2c/busses/i2c-mpc.c | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-) diff --git drivers/i2c/busses/i2c-mpc.c drivers/i2c/busses/i2c-mpc.c index 3d31879..c08f287 100644 --- drivers/i2c/busses/i2c-mpc.c +++ drivers/i2c/busses/i2c-mpc.c @@ -574,7 +574,23 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); } } - mpc_i2c_stop(i2c); + mpc_i2c_stop(i2c); /* Initiate STOP */ + orig_jiffies = jiffies; + /* Wait until STOP is seen, allow up to 1 s */ + while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) { + if (time_after(jiffies, orig_jiffies + HZ)) { + u8 status = readb(i2c->base + MPC_I2C_SR); + + dev_dbg(i2c->dev, "timeout\n"); + if ((status & (CSR_MCF | CSR_MBB | CSR_RXAK)) != 0) { + writeb(status & ~CSR_MAL, + i2c->base + MPC_I2C_SR); + mpc_i2c_fixup(i2c); + } + return -EIO; + } + cond_resched(); + } return (ret < 0) ? ret : num; }