i2c: rcar: handle difference in setting up non-first message

Signed-off-by: Ryo Kataoka <ryo.kataoka.wt@renesas.com>
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-rcar.c

@@ -92,6 +92,7 @@
 #define RCAR_IRQ_ACK_RECV	(~(MAT | MDR) & 0xFF)
 
 #define ID_LAST_MSG	(1 << 0)
+#define ID_FIRST_MSG	(1 << 1)
 #define ID_DONE		(1 << 2)
 #define ID_ARBLOST	(1 << 3)
 #define ID_NACK		(1 << 4)
@@ -254,13 +255,22 @@ static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
 	int read = !!rcar_i2c_is_recv(priv);
 
 	priv->pos = 0;
-	priv->flags = 0;
 	if (priv->msgs_left == 1)
 		rcar_i2c_flags_set(priv, ID_LAST_MSG);
 
 	rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | read);
-	rcar_i2c_write(priv, ICMSR, 0);
-	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+	/*
+	 * We don't have a testcase but the HW engineers say that the write order
+	 * of ICMSR and ICMCR depends on whether we issue START or REP_START. Since
+	 * it didn't cause a drawback for me, let's rather be safe than sorry.
+	 */
+	if (rcar_i2c_flags_has(priv, ID_FIRST_MSG)) {
+		rcar_i2c_write(priv, ICMSR, 0);
+		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+	} else {
+		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+		rcar_i2c_write(priv, ICMSR, 0);
+	}
 	rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);
 }
 
@@ -268,6 +278,7 @@ static void rcar_i2c_next_msg(struct rcar_i2c_priv *priv)
 {
 	priv->msg++;
 	priv->msgs_left--;
+	priv->flags = 0;
 	rcar_i2c_prepare_msg(priv);
 }
 
@@ -482,10 +493,10 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
 		}
 	}
 
-	/* init data */
+	/* init first message */
 	priv->msg = msgs;
 	priv->msgs_left = num;
-
+	priv->flags = ID_FIRST_MSG;
 	rcar_i2c_prepare_msg(priv);
 
 	time_left = wait_event_timeout(priv->wait,