On Fri, Jul 15, 2016 at 11:59:11AM +0200, 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. > > 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.sch...@free-electrons.com> > --- > > No modifications for this patch since we did not settled for a solution. > What should we do? > AFAICS the only thing we can do is to replace module_platform_driver() with its explicitly coded variant, and to use use late_initcall() instead of module_init(). Anything else would result in endless probe deferrals if there are no channels.
Guenter > drivers/hwmon/iio_hwmon.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c > index b550ba5..c0da4d9 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) {