1 files changed, 30 insertions, 11 deletions

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 886217f1ba61..5f4bc7008251 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -458,7 +458,7 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
         return 0;
 }
 
-static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
+static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg)
 {
         int i, result;
         unsigned int temp;
@@ -515,15 +515,30 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
                         msgs->len += len;
                 }
                 if (i == (msgs->len - 1)) {
-                        /* It must generate STOP before read I2DR to prevent
-                           controller from generating another clock cycle */
-                        dev_dbg(&i2c_imx->adapter.dev,
-                                "<%s> clear MSTA\n", __func__);
-                        temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
-                        temp &= ~(I2CR_MSTA | I2CR_MTX);
-                        imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
-                        i2c_imx_bus_busy(i2c_imx, 0);
-                        i2c_imx->stopped = 1;
+                        if (is_lastmsg) {
+                                /*
+                                 * It must generate STOP before read I2DR to prevent
+                                 * controller from generating another clock cycle
+                                 */
+                                dev_dbg(&i2c_imx->adapter.dev,
+                                        "<%s> clear MSTA\n", __func__);
+                                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+                                temp &= ~(I2CR_MSTA | I2CR_MTX);
+                                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+                                i2c_imx_bus_busy(i2c_imx, 0);
+                                i2c_imx->stopped = 1;
+                        } else {
+                                /*
+                                 * For i2c master receiver repeat restart operation like:
+                                 * read -> repeat MSTA -> read/write
+                                 * The controller must set MTX before read the last byte in
+                                 * the first read operation, otherwise the first read cost
+                                 * one extra clock cycle.
+                                 */
+                                temp = readb(i2c_imx->base + IMX_I2C_I2CR);
+                                temp |= I2CR_MTX;
+                                writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+                        }
                 } else if (i == (msgs->len - 2)) {
                         dev_dbg(&i2c_imx->adapter.dev,
                                 "<%s> set TXAK\n", __func__);
@@ -547,6 +562,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 {
         unsigned int i, temp;
         int result;
+        bool is_lastmsg = false;
         struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
 
         dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
@@ -558,6 +574,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 
         /* read/write data */
         for (i = 0; i < num; i++) {
+                if (i == num - 1)
+                        is_lastmsg = true;
+
                 if (i) {
                         dev_dbg(&i2c_imx->adapter.dev,
                                 "<%s> repeated start\n", __func__);
@@ -588,7 +607,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
                         (temp & I2SR_RXAK ? 1 : 0));
 #endif
                 if (msgs[i].flags & I2C_M_RD)
-                        result = i2c_imx_read(i2c_imx, &msgs[i]);
+                        result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
                 else
                         result = i2c_imx_write(i2c_imx, &msgs[i]);
                 if (result)