On Thu, 8 May 2014 14:33:39 -0600, Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx> wrote: > On Thu, May 08, 2014 at 06:37:49PM +0200, Sylwester Nawrocki wrote: > > This patch adds a helper function to unregister devices which > > were created by an of_platform_populate() call. The pattern > > used here can already be found in multiple drivers. This helper > > can now be used instead of repeating similar code in drivers. > > I have a driver that does this as well, and what I found is that the > remove must be in reverse order from the create or things explode, and > that assumes the DT is topologically sorted according to dependency > (so no deferred probe). That is the tip of a much larger problem that we don't have any good way to solve. There is no dependency tracking beyond the nature Linux driver model tree. For example, the removal of a GPIO driver has no way to tell users that it is going away, and so there is no way to force a driver remove when it happens. If we created a managed api for requesting resource (ie. devm_request_gpio()), then it would be possible for the gpio core to force a remove event on any driver that doesn't have the ability to gracefully handle a remove. The exact same problem exists for IRQs, clocks, regulators, or pretty much any cross-tree dependency. :-( > AFAIK, there is no analog to deferred probe for removal, and > attempting to remove, say, a GPIO driver while an I2C bit bang is using > it just fails. Indeed, it is a completely different operation. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
