[v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found
From: linux@roeck-us.net (Guenter Roeck)
Date: 2016-07-16 17:00:25
Also in:
linux-hwmon, linux-iio, lkml
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 <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(). Anything else would result in endless probe deferrals if there are no channels. Guenter
quoted hunk ↗ jump to hunk
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) {