i2c: uniphier: issue STOP only for last message or I2C_M_STOP

[ Upstream commit 38f5d8d8cbb2ffa2b54315118185332329ec891c ]

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: dd6fd4a32793 ("i2c: uniphier: add UniPhier FIFO-less 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/i2c/busses/i2c-uniphier.c b/drivers/i2c/busses/i2c-uniphier.c
index bb181b0..454f914 100644 (file)
--- a/drivers/i2c/busses/i2c-uniphier.c
+++ b/drivers/i2c/busses/i2c-uniphier.c
@@ -248,11 +248,8 @@ static int uniphier_i2c_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_i2c_master_xfer_one(adap, msg, stop);
                if (ret)