Re: [PATCH 0/7] MIPS: Move device-tree files to a common location

[Andrew Bresticker]

On Fri, Aug 22, 2014 at 4:16 PM, Jonas Gorski <jogo@xxxxxxxxxxx> wrote:
> On Sat, Aug 23, 2014 at 12:10 AM, Andrew Bresticker
> <abrestic@xxxxxxxxxxxx> wrote:
>> On Fri, Aug 22, 2014 at 1:57 PM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
>>> On 08/22/2014 01:42 PM, Florian Fainelli wrote:
>>>>
>>>> On Aug 21, 2014 3:05 PM, "Andrew Bresticker" <abrestic@xxxxxxxxxxxx
>>>> <mailto:abrestic@xxxxxxxxxxxx>> wrote:
>>>>  >
>>>>  > To be consistent with other architectures and to avoid unnecessary
>>>>  > makefile duplication, move all MIPS device-trees to arch/mips/boot/dts
>>>>  > and build them with a common makefile.
>>>>
>>>> I recall reading that the ARM organization for DTS files was a bit
>>>> unfortunate and should have been something like:
>>>>
>>>> arch/arm/boot/dts/<vendor>/
>>>>
>>>> Is this something we should do for the MIPS and update the other
>>>> architectures to follow that scheme?
>>>
>>>
>>> If we choose not to intermingle .dts files from all the vendors in a single
>>> directory, why do anything at all?  Currently the .dts files for a vendor
>>> are nicely segregated with the rest of the vendors code under a single
>>> directory.
>>>
>>> Personally I think things are fine as they are.  Any common code remaining
>>> in the Makefiles could be moved to the scripts directory for a smaller
>>> change.
>>
>> Assuming we don't move them to a common location just to segregate
>> them again, it makes MIPS consistent with every other architecture
>> (not just ARM!) using DT.  It also makes it easier to introduce common
>> changes later on, like the 'dtbs' or 'dtbs_install' make targets.
>
> I think having dts files under a predictable location is a good idea,
> especially if it allows common code/targets as "dtbs".
>
> Maybe a totally insane idea, but how this for having the cake and eating it too:
>
> arch/mips/boot/dts/*.dts => dts files to be built along side the kernel as .dtbs
>
> arch/mips/<mach>/*.dts => dts files built into the kernel
>
> (the ../*.dts isn't meant as they should be in the top directory, just
> somewhere in that sub tree)
>
> Because I can see a use case where you want both. For example octeon
> uses generic device tree boards to use as a basis if the bootloader
> did not provide one/is too old, but maybe also provide dts files for
> known boards, which shouldn't be included in the kernel binary itself.

I'm not sure I like having DTs in both the common and per-platform
directories, but this is a use case I've been think about as well.
What I'm thinking is: have "make dtbs" build all applicable DTBs for
the selected platform and, based on other config options, build some
subset of those DTBs in the kernel.  For example: if CONFIG_RALINK,
"make dtbs" builds all the {mt,rt}*_eval.dtb's and, when building the
kernel, one of those dtbs may be built into the kernel based on which
CONFIG_DTB_RT* option is selected (if any).  I'm not sure yet what the
cleanest way to do that is though.
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