From: Tim Harvey <tharvey@gateworks.com>
Subject: [PATCH] i2c: imx: retry on NAK

In case of busy i2c try again to get ACK.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Luka Perkov <luka@openwrt.org>
---
 drivers/i2c/busses/i2c-imx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -62,6 +62,7 @@
 
 /* Default value */
 #define IMX_I2C_BIT_RATE	100000	/* 100kHz */
+#define IMX_I2C_MAX_RETRIES	3	/* number of retries to attempt */
 
 /* IMX I2C registers */
 #define IMX_I2C_IADR	0x00	/* i2c slave address */
@@ -198,7 +199,7 @@ static int i2c_imx_acked(struct imx_i2c_
 {
 	if (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_RXAK) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
-		return -EIO;  /* No ACK */
+		return -EAGAIN; /* try again */
 	}
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> ACK received\n", __func__);
@@ -533,6 +534,7 @@ static int __init i2c_imx_probe(struct p
 	i2c_imx->adapter.dev.parent	= &pdev->dev;
 	i2c_imx->adapter.nr 		= pdev->id;
 	i2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
+	i2c_imx->adapter.retries	= IMX_I2C_MAX_RETRIES;
 	i2c_imx->base			= base;
 
 	pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
