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>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index e71fd40..3ed1f0a 100644 (file)
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/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,