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, 4 insertions, 2 deletions

diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 37f35388a2ae..8dc0164bd51e 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -202,8 +202,10 @@ static int __devinit pca953x_probe(struct i2c_client *client,
         int ret;
 
         pdata = client->dev.platform_data;
-        if (pdata == NULL)
-                return -ENODEV;
+        if (pdata == NULL) {
+                dev_dbg(&client->dev, "no platform data\n");
+                return -EINVAL;
+        }
 
         chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
         if (chip == NULL)