i2c: xiic: must always write 16-bit words to TX_FIFO

The TX_FIFO register is 10 bits wide.  The lower 8 bits are the data to be
written, while the upper two bits are flags to indicate stop/start.

The driver apparently attempted to optimize write access, by only writing a
byte in those cases where the stop/start bits are zero.  However, we have
seen cases where the lower byte is duplicated onto the upper byte by the
hardware, which causes inadvertent stop/starts.

This patch changes the write access to the transmit FIFO to always be 16 bits
wide.

Signed off by: Steven A. Falco <sfalco@harris.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index 332c720fb3fe..3d0f0520c1b4 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -312,10 +312,8 @@ static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
                         /* last message in transfer -> STOP */
                         data |= XIIC_TX_DYN_STOP_MASK;
                         dev_dbg(i2c->adap.dev.parent, "%s TX STOP\n", __func__);
-
-                        xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
-                } else
-                        xiic_setreg8(i2c, XIIC_DTR_REG_OFFSET, data);
+                }
+                xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
         }
 }