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authorAlok Chauhan <alokc@nvidia.com>2012-04-02 11:23:02 +0530
committerWolfram Sang <w.sang@pengutronix.de>2012-04-22 21:29:05 +0200
commitf70893d08338b9cab8008d2e30404ce58930a513 (patch)
tree69ae57606254ebe2598791895cea425143f25d41 /drivers/i2c
parent6c557cfee08751d22aed34840f389b846f0f4508 (diff)
downloadop-kernel-dev-f70893d08338b9cab8008d2e30404ce58930a513.zip
op-kernel-dev-f70893d08338b9cab8008d2e30404ce58930a513.tar.gz
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>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-tegra.c8
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..55e5ea6 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)
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