From: Ludovic Desroches <redacted>

If the i2c message length is zero, i2c-at91 will directly return an error
instead of trying to send a zero-length message.

Signed-off-by: Ludovic Desroches <redacted>
---

fix for 3.7

  drivers/i2c/busses/i2c-at91.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index aa59a25..eaddc77 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c

@@ -263,6 +263,9 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
  	unsigned int_addr_flag = 0;
  	struct i2c_msg *m_start = msg;

+	if (!msg->len)
+		return -EINVAL;
+
  	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);

  	/*