On Tue, May 24, 2011 at 10:03:35AM -0500, Rob Herring wrote:

Grant,

On 05/23/2011 10:09 AM, Grant Likely wrote:

quoted

On Mon, May 23, 2011 at 3:58 AM, Russell King - ARM Linux
[off-list ref]  wrote:

quoted

On Mon, May 23, 2011 at 11:37:04AM +0200, Kristoffer Glembo wrote:

quoted

Grant Likely wrote:

quoted

In the case we're talking about the bus really is an AMBA bus, and all
the devices on it are in some sense real amba devices.  The problem is
that not all of the devices on the bus implement peripheral ID
registers or other mechanisms that good upstanding AMBA devices are
expected to have.

Before we go hardware bashing of non primecell AMBA devices I would just
want to point out that the primecell stuff is not part of the AMBA
specification.

And before we go down that route, let me point out that the 'amba bus'
stuff in the kernel is there to support primecells, rather than all
devices which the AMBA specification covers.

The reason it's called 'amba' is because back in 2001 or so when the
first primecell drivers were created, there was little information
available as to what AMBA, AHB, or APB even covered.  All I had to go
on were the primecell documents themselves.  The higher level documents
were not available to me.

So, despite it being called 'amba', it really is just for primecells
and if we didn't have the exposure to userspace, I'd have renamed it to
'apb' or similar instead.

Okay, that clarifies things a lot, and lends weight to the arguement
that it is perfectly normal and acceptable to have both amba_devices
and platform_devices on the same bus segment.  Are there any cases
where amba primecells are being driven by platform_drivers?  If so,
should those drivers have an amba_driver registration added?

I would be surprised if there are any implemented as
platform_drivers that are not duplicates of an amba driver. The STMP
uart is actually a pl011 and it's platform driver was recently

It (duart than auart) is a platform driver in Freesccale BSP, and was
turned into 'amba' one when being upstreamed.

removed IIRC. So I think we can consider platform drivers something
that should be fixed in this case.

-- 
Regards,
Shawn