From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934329Ab2C3MG5 (ORCPT ); Fri, 30 Mar 2012 08:06:57 -0400 Received: from hqemgate04.nvidia.com ([216.228.121.35]:17759 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933847Ab2C3MGu (ORCPT ); Fri, 30 Mar 2012 08:06:50 -0400 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Fri, 30 Mar 2012 05:06:50 -0700 From: Alok Chauhan To: , , , , , , , , , , , CC: , Subject: [PATCH] i2c: tegra: Add delay before reset the controller Date: Fri, 30 Mar 2012 17:36:19 +0530 Message-ID: <1333109179-12445-1-git-send-email-alokc@nvidia.com> X-Mailer: git-send-email 1.7.4.1 X-NVConfidentiality: public MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In NACK error condition, I2C controller violates clock-to-data setup time before stop. In Software, because of this reset of controller is happening before I2C controller could complete STOP condition. Added delay of 2 clock period before reset the controller in case of NACK error. Signed-off-by: Alok Chauhan --- delay will be calculated based on clock frequency of the bus. drivers/i2c/busses/i2c-tegra.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c index e978635..344282e 100644 --- a/drivers/i2c/busses/i2c-tegra.c +++ b/drivers/i2c/busses/i2c-tegra.c @@ -516,6 +516,14 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev, if (likely(i2c_dev->msg_err == I2C_ERR_NONE)) return 0; + /* + * In NACK error condition resetting of I2C controller happens + * before STOP condition is properly completed by I2C controller, + * so wait for 2 clock cycle to complete STOP condition. + */ + if (i2c_dev->msg_err == I2C_ERR_NO_ACK) + udelay(DIV_ROUND_UP(2 * 1000000, i2c_dev->bus_clk_rate)); + tegra_i2c_init(i2c_dev); if (i2c_dev->msg_err == I2C_ERR_NO_ACK) { if (msg->flags & I2C_M_IGNORE_NAK) -- 1.7.4.1