| From: "Steven A. Falco" <sfalco@harris.com> |
| Date: Mon, 22 Apr 2013 09:34:39 +0000 |
| Subject: i2c: xiic: must always write 16-bit words to TX_FIFO |
| |
| commit c39e8e4354ce4daf23336de5daa28a3b01f00aa6 upstream. |
| |
| 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> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| drivers/i2c/busses/i2c-xiic.c | 6 ++---- |
| 1 file changed, 2 insertions(+), 4 deletions(-) |
| |
| --- a/drivers/i2c/busses/i2c-xiic.c |
| +++ b/drivers/i2c/busses/i2c-xiic.c |
| @@ -311,10 +311,8 @@ static void xiic_fill_tx_fifo(struct xii |
| /* 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); |
| } |
| } |
| |
