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    SubjectRe: [PATCH 2/2] drivers/amba: probe via device tree
    On Tue, May 24, 2011 at 10:03:35AM -0500, Rob Herring wrote:
    > Grant,
    > On 05/23/2011 10:09 AM, Grant Likely wrote:
    > >On Mon, May 23, 2011 at 3:58 AM, Russell King - ARM Linux
    > ><> wrote:
    > >>On Mon, May 23, 2011 at 11:37:04AM +0200, Kristoffer Glembo wrote:
    > >>>Grant Likely wrote:
    > >>>>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.


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