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

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@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')
Cc: stable@vger.kernel.org # v3.11+
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

diff --git a/drivers/memory/mvebu-devbus.c b/drivers/memory/mvebu-devbus.c
index 110c036..b59a17f 100644 (file)
--- a/drivers/memory/mvebu-devbus.c
+++ b/drivers/memory/mvebu-devbus.c
@@ -108,8 +108,19 @@ 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);