[3.11.y.z extended stable] Patch "memory: mvebu-devbus: fix the conversion of the bus width" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    memory: mvebu-devbus: fix the conversion of the bus width

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 7a3a7ccc3425b36b515cfb7b38e766fee632fa59 Mon Sep 17 00:00:00 2001
From: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Date: Mon, 14 Apr 2014 17:29:18 +0200
Subject: memory: mvebu-devbus: fix the conversion of the bus width

commit ce965c3d2e68c5325dd5624eb101d70423022fef upstream.

According to the Armada 370 and Armada XP datasheets, the part of the
Device Bus register that configure the bus width should contain 0 for
a 8 bits bus width, and 1 for a 16 bits bus width (other values are
unsupported/reserved).

However, the current conversion done in the driver to convert from a
bus width in bits to the value expected by the register leads to
setting the register to 1 for a 8 bits bus, and 2 for a 16 bits bus.

This mistake was compensated by a mistake in the existing Device Tree
files for Armada 370/XP platforms: they were declaring a 8 bits bus
width, while the hardware in fact uses a 16 bits bus width.

This commit fixes that by adjusting the conversion logic.

This patch fixes a bug that was introduced in
3edad321b1bd2e6c8b5f38146c115c8982438f06 ('drivers: memory: Introduce
Marvell EBU Device Bus driver'), which was merged in v3.11.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Link: https://lkml.kernel.org/r/1397489361-5833-2-git-send-email-thomas.petazzoni@free-electrons.com
Fixes: 3edad321b1bd ('drivers: memory: Introduce Marvell EBU Device Bus driver')
Acked-by: Ezequiel Garcia <ezequiel.garcia at free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
Signed-off-by: Jason Cooper <jason at lakedaemon.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/memory/mvebu-devbus.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/memory/mvebu-devbus.c b/drivers/memory/mvebu-devbus.c
index 978e8e3abc5c..ae3bfeceb980 100644
--- a/drivers/memory/mvebu-devbus.c
+++ b/drivers/memory/mvebu-devbus.c
@@ -116,8 +116,19 @@ static int devbus_set_timing_params(struct devbus *devbus,
 			node->full_name);
 		return err;
 	}
-	/* Convert bit width to byte width */
-	r.bus_width /= 8;
+
+	/*
+	 * The bus width is encoded into the register as 0 for 8 bits,
+	 * and 1 for 16 bits, so we do the necessary conversion here.
+	 */
+	if (r.bus_width == 8)
+		r.bus_width = 0;
+	else if (r.bus_width == 16)
+		r.bus_width = 1;
+	else {
+		dev_err(devbus->dev, "invalid bus width %d\n", r.bus_width);
+		return -EINVAL;
+	}

 	err = get_timing_param_ps(devbus, node, "devbus,badr-skew-ps",
 				 &r.badr_skew);
--
1.9.1