Messages in this thread | | | Date | Sat, 7 Jul 2018 17:59:21 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH v2] driver core: add a debugfs entry to show deferred devices |
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On Thu, Jun 28, 2018 at 12:06:56AM +0200, Javier Martinez Canillas wrote: > With Device Trees (DT), the dependencies of the devices are defined in the > DT, then the drivers parse that information to lookup the needed resources > that have as dependencies. > > Since drivers and devices are registered in a non-deterministic way, it is > possible that a device that is a dependency has not been registered yet by > the time that is looked up. > > In this case the driver that requires this dependency cannot probe and has > to defer it. So the driver core adds it to a list of deferred devices that > is iterated again every time that a new driver is probed successfully. > > For debugging purposes it may be useful to know what are the devices whose > probe function was deferred. Add a debugfs entry showing that information. > > $ cat /sys/kernel/debug/devices_deferred > 48070000.i2c:twl@48:bci > musb-hdrc.0.auto > omapdrm.0 > > This information could be obtained partially by enabling debugging, but it > means that the kernel log has to be parsed and the probe deferral balanced > with the successes. This can be error probe and has to be done in a ad-hoc > manner by everyone who needs to debug these kind of issues. > > Since the information is already known by the kernel, just show it to make > it easier to debug. > > Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> > Reviewed-by: Mark Brown <broonie@kernel.org>
This doesn't apply to my tree anymore :(
Can you rebase and resend?
thanks,
greg k-h
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