[PATCH 3.10 027/173] i2c: mux: gpio: use reg value for i2c_add_mux_adapter

Greg Kroah-Hartman
2013-12-02T21:14:26Z

From: Ionut Nicu <ioan.nicu.ext@nsn.com>

commit 8c0ec2500eeb89749341884a972860d7f9e56f9c upstream.

The i2c-mux driver requires that the chan_id parameter
passed to the i2c_add_mux_adapter() function is equal
to the reg value for that adapter:

for_each_child_of_node(mux_dev->of_node, child) {
ret = of_property_read_u32(child, "reg", &reg);
if (ret)
continue;
if (chan_id == reg) {
priv->adap.dev.of_node = child;
break;
}
}

The i2c-mux-gpio driver uses an internal logical index
for chan_id when calling i2c_add_mux_adapter() instead
of using the reg value.

Because of this, there will problems in selecting the
right adapter when the i2c-mux-gpio's index into
mux->data.values doesn't match the reg value.

An example of such a case:

mux->data.values = { 1, 0 }

For chan_id = 0, i2c-mux will bind the adapter to the
of_node with reg = <0>, but when it will call the
select() callback with chan_id set to 0, the i2c-mux-gpio
will use it as an index into mux->data.values and it will
actually select the bus with reg = <1>.

Signed-off-by: Ionut Nicu <ioan.nicu.ext@nsn.com>
Acked-by: Alexander Sverdlin <alexander.sverdlin@nsn.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/i2c/muxes/i2c-mux-gpio.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -39,7 +39,7 @@ static int i2c_mux_gpio_select(struct i2
{
struct gpiomux *mux = data;

- i2c_mux_gpio_set(mux, mux->data.values[chan]);
+ i2c_mux_gpio_set(mux, chan);

return 0;
}
@@ -223,7 +223,7 @@ static int i2c_mux_gpio_probe(struct pla
unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;

mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
- i, class,
+ mux->data.values[i], class,
i2c_mux_gpio_select, deselect);
if (!mux->adap[i]) {
ret = -ENODEV;