[PATCH 2/7] ARM: dts: skeleton: add unit name to memory node

[Rob Herring]

On Thu, Mar 31, 2016 at 11:27 AM, Rob Herring <robh+dt at kernel.org> wrote:
> On Wed, Mar 30, 2016 at 11:15 AM, Joachim  Eastwood <manabian at gmail.com> wrote:
>> Hi Mark,
>>
>> On 30 March 2016 at 15:41, Mark Rutland <mark.rutland at arm.com> wrote:
>>> On Wed, Mar 30, 2016 at 04:06:56PM +0300, Vladimir Zapolskiy wrote:
>>>> On 30.03.2016 14:06, Mark Rutland wrote:
>>>> > On Wed, Mar 30, 2016 at 12:30:41AM +0200, Joachim Eastwood wrote:
>>>> >> Add unit name to memory to remove the following warning:
>>>> >>  Warning (unit_address_vs_reg): Node /memory has a reg or ranges
>>>> >>                            property, but no unit name
>>>> >
>>>> > If anything, it would be better to get rid of the memory node from the
>>>> > skeleton DTs.
>>>> >
>>>> > For DTs which have a memory node there's no problem, and DTs which
>>>> > expect a bootlaoder to fill things in have a logical place to document
>>>> > that fact.
>>>
>>>> The only problem I see if DTB is updated on a board but a board bootloader
>>>> on fix-up is capable to fill a preexisting "/memory" device node in only,
>>>> otherwise it is not clear why the device node is present in skeleton.dtsi.
>>>
>>> Sure. To clarify the above, what I expect that for this case is that the
>>> empty memory node would exist in the dts for that particular board,
>>> along with a comment, e.g.
>>>
>>>         /* The firmware/bootloader for $BOARD fills this in */
>>>         memory {
>>>                 device_type = "memory";
>>>                 reg = <0 0 0 0>;
>>>         };
>>
>> To avoid the warning with the new dtc this would need to be memory at 0.
>
> Except memory is probably not actually at 0 here. This has come up
> before and been beaten to death. Bottom line is plain "memory" is
> allowed, and I plan to add that exception to dtc.
>
>>> That way you can tell at a glance that the lack of memory information in
>>> the DT for a board is intentional, and the bootloader still gets the
>>> node it expects.
>>
>>
>> But this doesn't seem to be a "problem" with any of the DTs in
>> arch/arm/boot as they all defined a memory node.
>>
>> I used the following script to check for the memory node in all built dtb's.
>>   make ARCH=arm CONFIG_OF_ALL_DTBS=y dtbs
>>   for i in $(ls arch/arm/boot/dts/*.dtb); do
>>          m=$(scripts/dtc/dtc -I dtb -O dts $i | grep -m1 'memory.*{')
>>          if [ -z "$m" ]; then
>>                  echo "Missing memory node in $i"
>>           fi
>>   done
>>
>> So it should be pretty safe to just remove the memory node entry in
>> the skeleton files. Unless I have missed something with the script
>> above.
>
> You've got to make sure they have 'device_type = "memory";' which they
> could rely on inheriting.

BTW, you could add this as a check to dtc and then it will find all
the missing ones for you.

Rob