gpio: fix probe() error return in gpio driver probes

A number of drivers in drivers/gpio return -ENODEV when confronted with
missing setup parameters such as the platform data.  However, returning
-ENODEV causes the driver layer to silently ignore the driver as it
assumes the probe did not find anything and was only speculative.

To make life easier to discern why a driver is not being attached, change
to returning -EINVAL, which is a better description of the fact that the
driver data was not valid.

Also add a set of dev_dbg() statements to the error paths to provide an
better explanation of the error as there may be more that one point in the
driver.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/gpio/pcf857x.c b/drivers/gpio/pcf857x.c
index 4bc2070dd4a1..9525724be731 100644
--- a/drivers/gpio/pcf857x.c
+++ b/drivers/gpio/pcf857x.c
@@ -188,8 +188,10 @@ static int pcf857x_probe(struct i2c_client *client,
         int                             status;
 
         pdata = client->dev.platform_data;
-        if (!pdata)
-                return -ENODEV;
+        if (!pdata) {
+                dev_dbg(&client->dev, "no platform data\n");
+                return -EINVAL;
+        }
 
         /* Allocate, initialize, and register this gpio_chip. */
         gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
@@ -248,8 +250,10 @@ static int pcf857x_probe(struct i2c_client *client,
                 else
                         status = i2c_read_le16(client);
 
-        } else
-                status = -ENODEV;
+        } else {
+                dev_dbg(&client->dev, "unsupported number of gpios\n");
+                status = -EINVAL;
+        }
 
         if (status < 0)
                 goto fail;