Re: [PATCH v3 1/4] hwmon: iio_hwmon: delay probing with late_initcall

Alexander Stein
2016-07-26T09:05:49Z

On Tuesday 26 July 2016 10:24:48, Quentin Schulz wrote:
> On 26/07/2016 10:21, Alexander Stein wrote:
> > On Tuesday 26 July 2016 09:43:44, Quentin Schulz wrote:
> >> 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.
> >
> > Would it work if iio_channel_get_all returning ENODEV is used for
> > returning
> > EPROBE_DEFER in iio_channel_get_all? Using late initcalls for
> > driver/device
> > dependencies seems not right for me at this place.
>
> Then what if the iio_channel_get_all is called outside of the probe of a
> driver? We'll have to change the error code, things we are apparently
> trying to avoid (see v2 patches' discussions).

Maybe I didn't express my idea enough. I don't want to change the behavior of
iio_channel_get_all at all. Just the result evaluation of iio_channel_get_all
in iio_hwmon_probe. I have something link the patch below in mind.

Best regards,
Alexander
---
diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c
index b550ba5..e32d150 100644
--- a/drivers/hwmon/iio_hwmon.c
+++ b/drivers/hwmon/iio_hwmon.c
@@ -73,8 +73,12 @@ static int iio_hwmon_probe(struct platform_device *pdev)
name = dev->of_node->name;

channels = iio_channel_get_all(dev);
- if (IS_ERR(channels))
- return PTR_ERR(channels);
+ if (IS_ERR(channels)) {
+ if (PTR_ERR(channels) == -ENODEV)
+ return -EPROBE_DEFER;
+ else
+ return PTR_ERR(channels);
+ }

st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
if (st == NULL) {