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

[Rob Herring]

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.

Rob