From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Mon, 18 Jul 2016 12:02:32 +0200 Subject: [v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found In-Reply-To: <20160716170013.GA27490@roeck-us.net> References: <1468576754-3273-2-git-send-email-quentin.schulz@free-electrons.com> <20160716170013.GA27490@roeck-us.net> Message-ID: <20160718100232.GE4199@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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: > > 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 > > --- > > > > 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 -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: not available URL: