hwmon: (iio_hwmon) defer probe when no channel is found

iio_channel_get_all returns -ENODEV when it cannot find either phandles and
properties in the Device Tree or channels whose consumer_dev_name matches
iio_hwmon in iio_map_list. The iio_map_list is filled in by iio drivers
which might be probed after iio_hwmon.

It is better to defer the probe of iio_hwmon if such error is returned by
iio_channel_get_all in order to let a chance to iio drivers to expose
channels in iio_map_list.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c
index 89449871bca7..f6a76679c650 100644
--- a/drivers/hwmon/iio_hwmon.c
+++ b/drivers/hwmon/iio_hwmon.c
@@ -73,8 +73,11 @@ static int iio_hwmon_probe(struct platform_device *pdev)
                 name = dev->of_node->name;
 
         channels = iio_channel_get_all(dev);
-        if (IS_ERR(channels))
+        if (IS_ERR(channels)) {
+                if (PTR_ERR(channels) == -ENODEV)
+                        return -EPROBE_DEFER;
                 return PTR_ERR(channels);
+        }
 
         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
         if (st == NULL) {