i2c: rcar: rework hw init

BugLink: https://bugs.launchpad.net/bugs/1776177

commit 2c78cdc1 upstream.

We don't need to init HW before every transfer since we know the HW
state then. HW init at probe time is enough. While here, add setting the
clock register which belongs to init HW. Also, set MDBS bit since not
setting it is prohibited according to the manual.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Chris Paterson <Chris.Paterson2@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/i2c/busses/i2c-rcar.c

@@ -144,9 +144,10 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
 {
 	/* reset master mode */
 	rcar_i2c_write(priv, ICMIER, 0);
-	rcar_i2c_write(priv, ICMCR, 0);
+	rcar_i2c_write(priv, ICMCR, MDBS);
 	rcar_i2c_write(priv, ICMSR, 0);
-	rcar_i2c_write(priv, ICMAR, 0);
+	/* start clock */
+	rcar_i2c_write(priv, ICCCR, priv->icccr);
 }
 
 static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
@@ -496,16 +497,6 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
 
 	pm_runtime_get_sync(dev);
 
-	/*-------------- spin lock -----------------*/
-	spin_lock_irqsave(&priv->lock, flags);
-
-	rcar_i2c_init(priv);
-	/* start clock */
-	rcar_i2c_write(priv, ICCCR, priv->icccr);
-
-	spin_unlock_irqrestore(&priv->lock, flags);
-	/*-------------- spin unlock -----------------*/
-
 	ret = rcar_i2c_bus_barrier(priv);
 	if (ret < 0)
 		goto out;
@@ -666,6 +657,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto out_pm_put;
 
+	rcar_i2c_init(priv);
 	pm_runtime_put(dev);
 
 	irq = platform_get_irq(pdev, 0);