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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        Ben Hutchings <ben.hutchings@codethink.co.uk>
Subject: [PATCH 4.9 09/52] i2c: rcar: fix resume by always initializing registers before transfer
Date:   Tue, 10 Jul 2018 20:24:37 +0200
Message-Id: <20180710182450.429872333@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

commit ae481cc139658e89eb3ea671dd00b67bd87f01a3 upstream.

Resume failed because of uninitialized registers. Instead of adding a
resume callback, we simply initialize registers before every transfer.
This lightweight change is more robust and will keep us safe if we ever
need support for power domains or dynamic frequency changes.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-rcar.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -700,6 +700,8 @@ static int rcar_i2c_master_xfer(struct i
 
 	pm_runtime_get_sync(dev);
 
+	rcar_i2c_init(priv);
+
 	ret = rcar_i2c_bus_barrier(priv);
 	if (ret < 0)
 		goto out;
@@ -857,8 +859,6 @@ static int rcar_i2c_probe(struct platfor
 	if (ret < 0)
 		goto out_pm_put;
 
-	rcar_i2c_init(priv);
-
 	/* Don't suspend when multi-master to keep arbitration working */
 	if (of_property_read_bool(dev->of_node, "multi-master"))
 		priv->flags |= ID_P_PM_BLOCKED;