From: Alok Chauhan Date: Mon, 2 Apr 2012 05:53:02 +0000 (+0530) Subject: i2c: tegra: Add delay before resetting the controller after NACK X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=f70893d08338;p=openwrt%2Fstaging%2Fblogic.git i2c: tegra: Add delay before resetting the controller after NACK NACK interrupt is generated before I2C controller generates the STOP condition on bus. Because of this reset of controller is happening before I2C controller could complete STOP condition. So wait for some time before resetting the controller so that STOP condition has delivered properly on bus. Added delay of 2 clock period before resetting the controller in case of NACK error. Signed-off-by: Alok Chauhan Acked-by: Stephen Warren [wsa: Reworded the commit msg and code comment a bit] Signed-off-by: Wolfram Sang --- diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c index e978635e60f0..55e5ea62ccee 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; + /* + * NACK interrupt is generated before the I2C controller generates the + * STOP condition on the bus. So wait for 2 clock periods before resetting + * the controller so that STOP condition has been delivered properly. + */ + 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)