i2c: fix i2c-sh_mobile rx underrun

Fix receive path underrun in i2c-sh_mobile driver.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c
index 640cbb237328..3384a717fec0 100644
--- a/drivers/i2c/busses/i2c-sh_mobile.c
+++ b/drivers/i2c/busses/i2c-sh_mobile.c
@@ -318,7 +318,8 @@ static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
                 } else
                         data = i2c_op(pd, OP_RX, 0);
 
-                pd->msg->buf[real_pos] = data;
+                if (real_pos >= 0)
+                        pd->msg->buf[real_pos] = data;
         } while (0);
 
         pd->pos++;