Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758219AbaKTV3r (ORCPT ); Thu, 20 Nov 2014 16:29:47 -0500 Received: from mail-lb0-f180.google.com ([209.85.217.180]:49677 "EHLO mail-lb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758095AbaKTV3H (ORCPT ); Thu, 20 Nov 2014 16:29:07 -0500 From: Alexander Kochetkov To: linux-omap@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, al.kochet@gmail.com Cc: Wolfram Sang , Tony Lindgren , Felipe Balbi Subject: [PATCH 3/4] i2c: omap: don't reset controller if Arbitration Lost detected Date: Fri, 21 Nov 2014 01:28:44 +0400 Message-Id: <1416518925-20679-4-git-send-email-al.kochet@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1416518925-20679-1-git-send-email-al.kochet@gmail.com> References: <1416518925-20679-1-git-send-email-al.kochet@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arbitration Lost is a expected situation in a multimaster environment. IP correctly detect it. The only reason for reseting IP in the AL case is to be sure to avoid advisory 1.94 (omap3) and errata i595 (omap4): "I2C: After an Arbitration is Lost the Module Incorrectly Starts the Next Transfer" with workaround: "The MST and STT bits inside I2C_CON should be set to 1 at the same moment (avoid setting the MST bit to 1 while STT = 0)." The driver never writes MST and STT bits separately and doesn't create condition for errata. So the reset is not necessary. Tested on Beagleboard XM C. Signed-off-by: Alexander Kochetkov --- drivers/i2c/busses/i2c-omap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 3ffb9c0..47103e7 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -707,13 +707,17 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap, return 0; /* We have an error */ - if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR | + if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | OMAP_I2C_STAT_XUDF)) { omap_i2c_reset(dev); __omap_i2c_init(dev); return -EIO; } + if (dev->cmd_err & OMAP_I2C_STAT_AL) { + return -EIO; + } + if (dev->cmd_err & OMAP_I2C_STAT_NACK) { if (msg->flags & I2C_M_IGNORE_NAK) return 0; -- 1.7.9.5 -- 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/