Re: [PATCH v2 1/3] devicetree: bindings: Document qcom,msm-id and qcom,board-id

[Rob Clark]

On Thu, Mar 5, 2015 at 8:59 PM, Olof Johansson <olof@xxxxxxxxx> wrote:
> On Thu, Mar 5, 2015 at 12:23 PM, Kumar Gala <galak@xxxxxxxxxxxxxx> wrote:
>>
>> On Mar 5, 2015, at 1:42 PM, Kevin Hilman <khilman@xxxxxxxxxx> wrote:
>>
>>> Kumar Gala <galak@xxxxxxxxxxxxxx> writes:
>>>
>>>> The top level qcom,msm-id and qcom,board-id are utilized by bootloaders
>>>> on Qualcomm MSM platforms to determine which device tree should be
>>>> utilized and passed to the kernel.
>>>>
>>>> Cc: <devicetree@xxxxxxxxxxxxxxx>
>>>> Signed-off-by: Kumar Gala <galak@xxxxxxxxxxxxxx>
>>>
>>> Is this the special magic that allows qcom bootloaders to take a kernel
>>> plus multiple DTBs and figure out which DTB to pass?
>>>
>>> Kevin
>>
>> yes
>
> That's a bummer.
>
> Luckily, the solution for upstream is still quite simple: Provide only
> one devicetree, and it'll be used, right?
>

I never managed to figure out how to get that to work (at least on my
apq8074 dragonboard.. fortunately ifc6540 seems to work w/ appended
dtb).. kind of a pita because it is a bit of a non-standard boot.img
format too..

Otoh getting an upstream (or even different kernel) kernel working can
be hard enough as-is on random different tablet/phone/etc.  Why not
make whoever tries' life a bit easier by allowing some nonsense node
into the qcom dtbs which makes it compatible w/ bootloaders already
out there in the field ;-)

BR,
-R

>
> -Olof
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