Re: [PATCH v2 4/4] ARM: DTS: AM43x: Add DSS node

[Mark Rutland <mark.rutland@arm.com>]

On Fri, Mar 14, 2014 at 09:42:26AM +0000, Tomi Valkeinen wrote:
> On 14/03/14 11:10, Mark Rutland wrote:
> 
> > The "simple-bus" compatible string is intended for busses which are
> > transparent (bar some address remapping expressed via ranges), and is
> > not intended as an annotation to get Linux to probe child nodes.
> > 
> > Any node with a "simple-bus" entry in the compatible list should either
> > be handled as a transparent bus, or optionally as the more specific bus
> > it claims to be (where some hardware configuration may be required
> > before children can be probed). Unfortunately Linux probes chidlren
> > regardless, which is arguable a Linux bug.
> > 
> > There's no reason to leak this issue into dts files. Please remove the
> > "simple-bus" string, and get the dss driver to probe children as
> > required -- as described above the dss node never makes sense as a
> > simple-bus.
> 
> Ok. I'll remove the simple-bus, and make the dss_core register the
> devices. I presume of_platform_populate() is fine for this? Seems to
> work fine for registration, but I haven't figured out yet how to
> unregister the devices (I get a crash in platform_device_del() if I just
> call platform_device_unregister for the submodules).

I think of_platform_populate should be ok. It's not fantastic -- all
child nodes will be probed, regardless of whether you expect them to
exist, but it's not as broken as using "simple-bus".

I'm unfortunately not familiar with how unregistration works.

I can't see anything obviously wrong in platform_device_del. Do you have
a backtrace?

Thanks,
Mark.