1 files changed, 28 insertions, 13 deletions

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index 1f41a4f89c08..8a873975cf12 100644
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -191,28 +191,43 @@ static void xlp9xx_i2c_drain_rx_fifo(struct xlp9xx_i2c_dev *priv)
         if (priv->len_recv) {
                 /* read length byte */
                 rlen = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
+
+                /*
+                 * We expect at least 2 interrupts for I2C_M_RECV_LEN
+                 * transactions. The length is updated during the first
+                 * interrupt, and the buffer contents are only copied
+                 * during subsequent interrupts. If in case the interrupts
+                 * get merged we would complete the transaction without
+                 * copying out the bytes from RX fifo. To avoid this now we
+                 * drain the fifo as and when data is available.
+                 * We drained the rlen byte already, decrement total length
+                 * by one.
+                 */
+
+                len--;
                 if (rlen > I2C_SMBUS_BLOCK_MAX || rlen == 0) {
                         rlen = 0;       /*abort transfer */
                         priv->msg_buf_remaining = 0;
                         priv->msg_len = 0;
-                } else {
-                        *buf++ = rlen;
-                        if (priv->client_pec)
-                                ++rlen; /* account for error check byte */
-                        /* update remaining bytes and message length */
-                        priv->msg_buf_remaining = rlen;
-                        priv->msg_len = rlen + 1;
+                        xlp9xx_i2c_update_rlen(priv);
+                        return;
                 }
+
+                *buf++ = rlen;
+                if (priv->client_pec)
+                        ++rlen; /* account for error check byte */
+                /* update remaining bytes and message length */
+                priv->msg_buf_remaining = rlen;
+                priv->msg_len = rlen + 1;
                 xlp9xx_i2c_update_rlen(priv);
                 priv->len_recv = false;
-        } else {
-                len = min(priv->msg_buf_remaining, len);
-                for (i = 0; i < len; i++, buf++)
-                        *buf = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
-
-                priv->msg_buf_remaining -= len;
         }
 
+        len = min(priv->msg_buf_remaining, len);
+        for (i = 0; i < len; i++, buf++)
+                *buf = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
+
+        priv->msg_buf_remaining -= len;
         priv->msg_buf = buf;
 
         if (priv->msg_buf_remaining)