Hi Guenter,

On Sat, Jul 16, 2016 at 10:00:13AM -0700, Guenter Roeck wrote:

On Fri, Jul 15, 2016 at 11:59:11AM +0200, Quentin Schulz wrote:

quoted

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 <redacted>
---

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().

I thought this kind of changes to the driver init time were
discouraged these days?

Anything else would result in endless probe deferrals if there are
no channels.

Well, technically, not endless. AFAIK, the kernel only retries when a
new driver is probed, which should hopefully settle down rather
quickly.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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