Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755006AbYLVOjI (ORCPT ); Mon, 22 Dec 2008 09:39:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754476AbYLVOi4 (ORCPT ); Mon, 22 Dec 2008 09:38:56 -0500 Received: from phoenix.clifford.at ([88.198.7.52]:34373 "EHLO phoenix.clifford.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754198AbYLVOiz (ORCPT ); Mon, 22 Dec 2008 09:38:55 -0500 X-Greylist: delayed 1470 seconds by postgrey-1.27 at vger.kernel.org; Mon, 22 Dec 2008 09:38:55 EST Date: Mon, 22 Dec 2008 14:55:42 +0100 From: Clifford Wolf To: LKML Cc: Adrian Cox Subject: [PATCH] Fixed i2c-mpc driver for multi-master i2c busses. Message-ID: <20081222135542.GA7317@clifford.at> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1881 Lines: 76 Fixed i2c-mpc driver for multi-master i2c busses. Simply retry on arbitration lost until xfer is successfull, a non-arbitration-lost error is triggered or the 1s timeout is hit. Tested with a freescale MPC8349E host cpu. Signed-off-by: Clifford Wolf --- ./drivers/i2c/busses/i2c-mpc.c (revision 2186) +++ ./drivers/i2c/busses/i2c-mpc.c (revision 2187) @@ -133,16 +133,16 @@ if (result < 0) return result; + if (x & CSR_MAL) { + pr_debug("I2C: MAL\n"); + return -EAGAIN; + } + if (!(x & CSR_MCF)) { pr_debug("I2C: unfinished\n"); return -EIO; } - if (x & CSR_MAL) { - pr_debug("I2C: MAL\n"); - return -EIO; - } - if (writing && (x & CSR_RXAK)) { pr_debug("I2C: No RXAK\n"); /* generate stop */ @@ -256,11 +256,11 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) { struct i2c_msg *pmsg; - int i; - int ret = 0; + int i, ret; unsigned long orig_jiffies = jiffies; struct mpc_i2c *i2c = i2c_get_adapdata(adap); +restart: mpc_i2c_start(i2c); /* Allow bus up to 1s to become not busy */ @@ -280,7 +280,7 @@ schedule(); } - for (i = 0; ret >= 0 && i < num; i++) { + for (i = 0, ret = 0; ret >= 0 && i < num; i++) { pmsg = &msgs[i]; pr_debug("Doing %s %d bytes to 0x%02x - %d of %d messages\n", pmsg->flags & I2C_M_RD ? "read" : "write", @@ -291,7 +291,13 @@ else ret = mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); + if (ret == -EAGAIN) { + pr_debug("Lost i2c arbitration -> retry.\n"); + mpc_i2c_stop(i2c); + goto restart; + } } + mpc_i2c_stop(i2c); return (ret < 0) ? ret : num; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/