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

From: Olof Johansson
Date: Tue Mar 10 2015 - 13:55:55 EST

On Tue, Mar 10, 2015 at 10:13 AM, Kumar Gala <galak@xxxxxxxxxxxxxx> wrote:
> On Mar 9, 2015, at 7:11 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
>> On Friday 06 March 2015 14:37:52 Kumar Gala wrote:
>>> On Mar 6, 2015, at 1:15 PM, Olof Johansson <olof@xxxxxxxxx> wrote:
>>>> On Fri, Mar 6, 2015 at 8:08 AM, Kumar Gala <galak@xxxxxxxxxxxxxx> wrote:
>>>>> On Mar 5, 2015, at 7:59 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?
>>>>> We can provide only one, we still need the IDs in the DT.
>>>> How are the DTS provided? Concatenated with the kernel, or in a
>>>> wrapped data format? Or in a separate partition from the kernel?
>>> Its a wrapped data format that is than concatenated with the kernel if I remember correctly.
>> Then you should be able to create a tool that can write this concatenated
>> format and insert these properties from a table that matches the boot
>> loader, right?
>> Arnd
> Are you suggesting the tool insert the properties in the DT? Iâm not sure I understand what the point of doing that would be.

To insert platform-local properties that mean nothing outside of the
firmware packaging of the device trees, which is the case here?

I think the idea of having the installer script inserting them is
quite reasonable in this case.

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