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    Subject[PATCH AUTOSEL 4.9 14/23] i2c: uniphier-f: issue STOP only for last message or I2C_M_STOP
    Date
    From: Masahiro Yamada <yamada.masahiro@socionext.com>

    [ Upstream commit 4c85609b08c4761eca0a40fd7beb06bc650f252d ]

    This driver currently emits a STOP if the next message is not
    I2C_MD_RD. It should not do it because it disturbs the I2C_RDWR
    ioctl, where read/write transactions are combined without STOP
    between.

    Issue STOP only when the message is the last one _or_ flagged with
    I2C_M_STOP.

    Fixes: 6a62974b667f ("i2c: uniphier_f: add UniPhier FIFO-builtin I2C driver")
    Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
    Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    drivers/i2c/busses/i2c-uniphier-f.c | 7 ++-----
    1 file changed, 2 insertions(+), 5 deletions(-)

    diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
    index db9105e52c79..0da4991dd356 100644
    --- a/drivers/i2c/busses/i2c-uniphier-f.c
    +++ b/drivers/i2c/busses/i2c-uniphier-f.c
    @@ -400,11 +400,8 @@ static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap,
    return ret;

    for (msg = msgs; msg < emsg; msg++) {
    - /* If next message is read, skip the stop condition */
    - bool stop = !(msg + 1 < emsg && msg[1].flags & I2C_M_RD);
    - /* but, force it if I2C_M_STOP is set */
    - if (msg->flags & I2C_M_STOP)
    - stop = true;
    + /* Emit STOP if it is the last message or I2C_M_STOP is set. */
    + bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);

    ret = uniphier_fi2c_master_xfer_one(adap, msg, stop);
    if (ret)
    --
    2.17.1
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