[PATCH 11/14] arm64: dts: Add initial device tree support for EXYNOS7

[Olof Johansson]

On Thu, Aug 28, 2014 at 10:54 AM, Rob Herring <robh at kernel.org> wrote:
> On Thu, Aug 28, 2014 at 12:19 PM, Olof Johansson <olof at lixom.net> wrote:
>> On Thu, Aug 28, 2014 at 10:03 AM, Mark Rutland <mark.rutland at arm.com> wrote:
>>> On Thu, Aug 28, 2014 at 05:28:22PM +0100, Olof Johansson wrote:
>>>> On Thu, Aug 28, 2014 at 2:48 AM, Mark Rutland <mark.rutland at arm.com> wrote:
>>>> > Hi,
>>>> >
>>>> >> > +   cpus {
>>>> >> > +           #address-cells = <2>;
>>>> >> > +           #size-cells = <0>;
>>>> >>
>>>> >> Why size-cells=2? Can you not fit a cpuid in 32 bits?
>>>> >
>>>> > As of commit 72aea393a2e7 (arm64: smp: honour #address-size when parsing
>>>> > CPU reg property) Linux can handle single-cell cpu node reg entries
>>>> > where /cpus/#address-cells = <1>.
>>>> >
>>>> > I can't make any guarantees about other code (e.g. bootloaders) which
>>>> > might try to do things with cpu nodes, YMMV.
>>>>
>>>> Ok. If address-cells is kept at 2 the unit address needs to be changed
>>>> to "0,0". So one or the other has to be changed.
>>>
>>> I'm happy either way.
>>>
>>> I'm not sure the rest of the tree had "0," prefixes on all of the
>>> unit-addresses for 64-bit addresses that were under 4GB, and I'm not
>>> sure that existing dts consistently do that either.
>>>
>>> Do we want to enforce that for all 64-bit unit-addresses?
>>
>> Yeah, I believe that's the only valid format for a 2-address-cell unit address.
>
> But we don't do leading 0's anywhere else like single cell unit
> addresses. Buses expressed with ranges and offsets are one example.
> Also, I2C addresses have a 32-bit size in DT yet are only 8-bit and we
> don't do leading zero's there.

Ok, I'm happily proven wrong here, also by confirming how this is done
on "real" OF.

According to benh:

15:20 <benh> ojn: 0,0 is not quite right, it's supposed to be used
when the two numbers are different things, like device,fn on PCI

The same is true for >2^32 unit addresses, they just use the one
integer instead of x,y.

So, I take back all I've said on this in the last 72 hours. :) It
looks like we might need to revisit some of the 32-bit DTs.  Simon,
drop the series you had. :)


-Olof