[RFC] early init and DT platform devices allocation/registration

[Thierry Reding]

On Wed, Jun 26, 2013 at 11:03:20AM +0100, Grant Likely wrote:
> On Wed, Jun 26, 2013 at 7:00 AM, Hiroshi Doyu <hdoyu at nvidia.com> wrote:
> > Grant Likely <grant.likely at secretlab.ca> wrote @ Tue, 25 Jun 2013 19:52:33 +0200:
> >
> >> > Here's my workaround. I need to call of_detach_node() with OF_DYNAMIC
> >> > to avoid duplicated device registration.
> >>
> >> Gah! my eyes!
> >>
> >> Don't do that. It is incredibly problematic. Look at inhibiting
> >> duplicate device creation instead.
> >
> > I may not follow this thread correctly, but could anyone point out the
> > above "inhibiting duplicate device creation" if there's already such
> > solution?
> 
> No, the solution doesn't exist yet, but it wouldn't be hard to
> implement. What you need to do is to add a struct device pointer to
> struct device_node, and set the pointer to the struct device when
> of_platform_device_create creates a device. (it would also need to be
> set for early_platform_device creation, but that's not something that
> should affect you). You would also add a check to
> of_platform_device_create to check if the device pointer is already
> set. If it is, then skip creation of the device.

One problem with this method is that every driver that needs or wants
the device early has to do it explicitly, but I guess we can't have it
all.

I find this solution rather appealing because it allows for instance the
Marvell Armada 370/XP IRQ chip driver to do this as well so we no longer
have to keep around the extra struct device_node * in msi_chip but we
can actually reuse the one from struct device instead.

Thierry
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