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 <alokc@nvidia.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
[wsa: Reworded the commit msg and code comment a bit]

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index e978635e60f04189e6478ccb112a0df4a2596ed3..55e5ea62ccee3b69148c13ce337a1ff8531bc467 100644 (file)
--- 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)