Re: [PATCH 1/1] of/overlay: of overlay callbacks

From: atull
Date: Wed Feb 24 2016 - 17:38:50 EST

On Mon, 22 Feb 2016, Rob Herring wrote:

> On Wed, Feb 17, 2016 at 11:41:25AM -0600, Alan Tull wrote:
> > Add overlay callback functionality.
> >
> > When DT overlays are being added, some drivers/subsystems
> > will want to know about the changes before they go into the
> > live tree. Similarly there is a need for post-remove
> > callbacks.
> >
> > Each handler is registered with a of_device_id. When
> > an overlay target matches a handler's id, the handler
> > gets called.
> >
> > The following 4 cases are handled: pre-apply, post-apply,
> > pre-remove, and post-remove.
> So I know I suggested maybe not using notifiers, but this ends up just
> looking like notifiers, so we might as well use them unless we somehow
> change the flow. You would just need to add pre-apply and pre-remove
> in of_attach_node and of_detach_node, right?

Just sent out a patch. Nobody calls of_attach_node or
of_detach_node so I had to add the notifiers elsewhere.

For overlays, I wanted to add a pointer to the overlay
fragment since pre-apply notifiers won't otherwise have that
information (unlike post-apply or pre-remove notifiers where
the overlay has already made it into the live tree).
That complicated the implementation a bit further.


> Rob