Re: [PATCH] ARM: tegra: Remove 0, prefix from unit-addresses

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 04/11/2016 12:32 PM, Rob Herring wrote:
> On Mon, Apr 11, 2016 at 11:05 AM, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
>> On 04/11/2016 08:01 AM, Thierry Reding wrote:
>>>
>>> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>>
>>> When Tegra124 support was first merged the unit-addresses of all devices
>>> were listed with a "0," prefix to encode the reg property's second cell.
>>> It turns out that this notation is not correct, and the "," separator is
>>> only used to separate fields in the unit address (such as the device and
>>> function number in PCI devices), not individual cells for addresses with
>>> more than one cell.
>>
>>
>>> diff --git a/arch/arm/boot/dts/tegra124-jetson-tk1.dts
>>> b/arch/arm/boot/dts/tegra124-jetson-tk1.dts
>>
>>
>>> -       gpu@0,57000000 {
>>> +       gpu@57000000 {
>>>                  /*
>>>                   * Node left disabled on purpose - the bootloader will
>>> enable
>>>                   * it after having set the VPR up
>>
>>
>> So the bootloader doesn't actually do that for the new node name at present.
>> I have written a patch to make it do so, but haven't sent it yet since I
>> wrote it in the middle of a large cleanup of U-Boot. I expect I can shuffle
>> it to the front of the series and send it soon though. Without a new
>> bootloader that contains this change, IIUC all graphics will be
>> non-operative if this change is applied.
>
> Then you should leave this one alone for a while.
>
> I also found this looking at u-boot:
>
> arch/arm/dts/tegra124.dtsi:     gpu@57000000 {

FWIW, that's because the U-Boot DTs use #address-cells=<1> on this chip 
so there was no question of using commas in the unit address or not. 
That may have been because U-Boot imported the DTs (or parts of them) 
from Linux before Linux switched to #address-cells=<2> on this chip.