[U-Boot] [PATCH] vexpress64: Juno: Change PCI buss addresses for IO to start from zero.

[Sudeep Holla]

On 22/11/16 15:08, Tom Rini wrote:
> On Tue, Nov 22, 2016 at 12:08:49PM +0000, Liviu Dudau wrote:
>> On Tue, Nov 22, 2016 at 11:29:20AM +0000, Sudeep Holla wrote:
>>> Hi Liviu,
>>>
>>> On Tue, Nov 22, 2016 at 11:19 AM, Liviu Dudau <Liviu.Dudau at foss.arm.com> wrote:
>>>> Juno uses a 1:1 mapping between CPU and PCI addresses for IO. First,
>>>> that will trip devices that cannot use more than 16 bits of addresses
>>>> for IO, second it is un-necessary as the system can handle zero-based
>>>> PCI addresses just fine.
>>>>
>>>> Change the mapping to start IO bus addresses from zero.
>>>>
>>>
>>> I assume this require corresponding DT change, shout if that's not true.
>>> If that's true, then does this patch not require patching of DT so
>>> that systems not
>>> running Uboot with this patch continue to work and we retain the
>>> mainline DT as is ?
>>
>> Yes, it does require DT changes, Jeremy Linton has a patch
>
> So to be clear, what level of coordination do we need between the two
> parts being merged?  It would not be ideal to have combinations of
> U-Boot and Linux not work.  Thanks!
>

What I had in mind is U-Boot modifying/fixing up the DT to adapt to this
change so that we maintain compatibility and don't break anything. But I
was not sure how feasible is that solution with other bootloaders like UEFI.

-- 
Regards,
Sudeep