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

[mark.rutland@arm.com (Mark Rutland)]

On Wed, Mar 30, 2016 at 06:15:35PM +0200, Joachim Eastwood wrote:
> Hi Mark,
> 
> On 30 March 2016 at 15:41, Mark Rutland <mark.rutland@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.

Hmm... That's a little sub-optimal in the case that a bootloader is
patching this. Presumably a bootloader that needs an existing node won't
patch the unit-address to match the reg (which might not start at 0).

I'd rather not have the unit-address than have an incorrect
unit-address, though I guess we don't have much of a choice here, unless
there's some override we can place in the dts.

> > 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.

The above might match reserved-memory nodes; it might be better to check
for 'device_type\s*=\s*"memory"'.

I assume that was run after deleting the memory node from the skeletons?

Otherwise, that looks fairly convincing!

Thanks,
Mark.