[PATCH 3.12 098/133] i2c: mv64xxx: Fix bus hang on A0 version of the Armada XP SoCs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.12-stable review patch.  If anyone has any objections, please let me know.

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

From: Gregory CLEMENT <gregory.clement@free-electrons.com>

commit 6cf70ae928bae17077efc0d528dec49bc380438b upstream.

The first variants of Armada XP SoCs (A0 stepping) have issues related
to the i2c controller which prevent to use the offload mechanism and
lead to a kernel hang during boot.

The commit introduces a new the compatible string
marvell,mv78230-a0-i2c for the i2c controller. When this compatible
string is used the driver disables the offload mechanism and the
kernel no more hangs on these SoCs.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reported-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 930ab3d403ae (i2c: mv64xxx: Add I2C Transaction Generator support)
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-mv64xxx.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -692,6 +692,7 @@ static const struct of_device_id mv64xxx
 	{ .compatible = "allwinner,sun4i-i2c", .data = &mv64xxx_i2c_regs_sun4i},
 	{ .compatible = "marvell,mv64xxx-i2c", .data = &mv64xxx_i2c_regs_mv64xxx},
 	{ .compatible = "marvell,mv78230-i2c", .data = &mv64xxx_i2c_regs_mv64xxx},
+	{ .compatible = "marvell,mv78230-a0-i2c", .data = &mv64xxx_i2c_regs_mv64xxx},
 	{}
 };
 MODULE_DEVICE_TABLE(of, mv64xxx_i2c_of_match_table);
@@ -783,6 +784,10 @@ mv64xxx_of_config(struct mv64xxx_i2c_dat
 		drv_data->errata_delay = true;
 	}
 
+	if (of_device_is_compatible(np, "marvell,mv78230-a0-i2c")) {
+		drv_data->offload_enabled = false;
+		drv_data->errata_delay = true;
+	}
 out:
 	return rc;
 #endif