Re: [PATCH 2/5] arm64, thunder: Add initial dts for Cavium Thunder SoC

[Robert Richter <robert.richter@caviumnetworks.com>]

On 28.08.14 16:01:08, Olof Johansson wrote:
> On Thu, Aug 28, 2014 at 11:14 AM, Robert Richter <rric@kernel.org> wrote:
> > On 28.08.14 09:31:43, Olof Johansson wrote:
> >> On Thu, Aug 28, 2014 at 9:25 AM, Mark Rutland <mark.rutland@arm.com> wrote:
> >> > On Thu, Aug 28, 2014 at 05:15:56PM +0100, Robert Richter wrote:
> >> >> Olof,
> >> >>
> >> >> On 30.07.14 11:14:23, Olof Johansson wrote:
> >> >> > On Wed, Jul 30, 2014 at 8:06 AM, Robert Richter <rric@kernel.org> wrote:
> >> >> > > From: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> >> >> > >
> >> >> > > Add initial device tree nodes for Cavium Thunder SoCs with support of
> >> >> > > 48 cores and gicv3. The dts file requires further changes, esp. for
> >> >> > > pci, gicv3-its and smmu. This changes will be added later together
> >> >> > > with the device drivers.
> >> >> > >
> >> >> > > Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> >> >> > > Signed-off-by: Robert Richter <rrichter@cavium.com>
> >> >> > > ---
> >> >> > >  arch/arm64/boot/dts/Makefile         |   1 +
> >> >> > >  arch/arm64/boot/dts/thunder-88xx.dts | 387 +++++++++++++++++++++++++++++++++++
> >> >> > >  2 files changed, 388 insertions(+)
> >> >> > >  create mode 100644 arch/arm64/boot/dts/thunder-88xx.dts
> >> >> > >
> >> >> > > diff --git a/arch/arm64/boot/dts/Makefile b/arch/arm64/boot/dts/Makefile
> >> >> > > index c52bdb051f66..f8001a62029c 100644
> >> >> > > --- a/arch/arm64/boot/dts/Makefile
> >> >> > > +++ b/arch/arm64/boot/dts/Makefile
> >> >> > > @@ -1,3 +1,4 @@
> >> >> > > +dtb-$(CONFIG_ARCH_THUNDER) += thunder-88xx.dtb
> >> >> > >  dtb-$(CONFIG_ARCH_VEXPRESS) += rtsm_ve-aemv8a.dtb foundation-v8.dtb
> >> >> > >  dtb-$(CONFIG_ARCH_XGENE) += apm-mustang.dtb
> >> >> >
> >> >> > Oh, and:
> >> >> >
> >> >> > Let's fix the mistake we made on 32-bit here (that we can't undo
> >> >> > unless we move all dts files now, which is too much churn), and put
> >> >> > each SoC vendor in its own subdirectory.
> >> >> >
> >> >> > So, please add a arch/arm64/boot/dts/cavium/ directory, add a Makefile
> >> >> > and the dts there.
> >> >> >
> >> >> > We should move vexpress under arm/   and xgene under apm/ too.
> >> >>
> >> >> I was looking into this. It turned out that this would introduce more
> >> >> pain than it solves. The problem with introducing vendor subdirs for
> >> >> .dts files is that this will require also subdirs for .dtb files to
> >> >> avoid name conflicts. This means that dtb files are no longer in a
> >> >> single directory. Current build scripts and makefiles rely on this.
> >> >> E.g.:
> >> >>
> >> >>  scripts/Makefile.lib:$(obj)/%.dtb.S: $(obj)/%.dtb
> >> >>
> >> >> Thus, the introduction of vendor subdirs is not easy to implement and
> >> >> may break existing workflows. Also, no other arch has vendor subdirs.
> >> >>
> >> >> A solution would be to have a naming scheme for dts files which
> >> >> requires the vendor in the file name, such as cavium-thunder-88xx.dtb.
> >> >> Though, these long names may look a bit ugly.
> >> >>
> >> >> Hmm... Any thoughts?
> >> >
> >> > That would make it possible to search, but the number of files in one
> >> > place might become somewhat overwelming (which I believe was Olof's
> >> > concern).
> >> >
> >> > Olof, thoughts?
> >>
> >> Yeah, on 32 bit we've got an ever-growing and very large directory
> >> today that is becoming a headache. Carving it up in directories to
> >> reduce plain directory size would come a long way.
> >>
> >> I think we would catch name conflicts quickly with the automatic
> >> builders we have today -- and it's likely that the files will have a
> >> platform prefix anyway so it shouldn't be a big issue. I think we can
> >> live with that.
> >
> > So you mean, having the source files with subdirectories, but the dtb
> > files in a single obj dir?

It seems it will be easier to have also subdirs for objs.

> Thinking about it a bit more, the even more obvious solution that I
> for some reason didn't think of at the time, is to have the
> dtbs_install target create the appropriate subdirectories on the
> install side, so that the structure is preserved.
> 
> That comes a bit closer to how modules are handled as well.

Yes, dtbs_install target would be useful.

Will come with a solution for this too.

-Robert