Re: [RFC V3 PATCH 5/7] arm64: dts: msm8994 SoC and Huawei Angler (Nexus 6P) support

[Michael Scott <michael.scott-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 10/12/2016 05:42 PM, Jeremy McNicoll wrote:
> On 2016-10-12 7:20 AM, Rob Herring wrote:
>> On Wed, Oct 12, 2016 at 8:34 AM, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> 
>> wrote:
>>> On Wed, Oct 12, 2016 at 02:37:32AM -0700, Jeremy McNicoll wrote:
>>>> +/ {
>>>> +     model = "HUAWEI MSM8994 ANGLER rev-1.01";
>>>> +     compatible = "qcom,msm8994";
>>>> +     qcom,board-id= <8026 0>;

Hello Jeremy,

When I tested these patches on linux-next, the bootloader on my Nexus 6P 
wasn't finding the dtb until I adjusted the board-id value to <8023 0>.

Apparently, my hardware matches "Huawei Technologies, Inc. MSM8994 
Angler VN2" in the original kernel sources:
https://android.googlesource.com/kernel/msm/+/android-msm-angler-3.10-nougat/arch/arm64/boot/dts/huawei/huawei_angler_vn2.dts

I'm not sure what the most common hardware is out in the wild, but the 
board-id for your dts comes from this commit, which seems to indicate 
it's a DVT model (as opposed to a PVT model):
https://android.googlesource.com/kernel/msm/+/e9a476191862cfe8e5e30e2babc04052f9ab936b

We should definitely get a sample size of > 1

- Mike

>>>> +};
>>>
>>> This last property is undocumented, and unused.
>>
>> They are required by the bootloader which AIUI can't/won't be updated
>> to use the mainline compatible string. The alternative is leave them
>
> That is my understanding as well after talking to some QC people over
> beer the other night.
>
>> out and then you have to run the dtb thru QC's dtbTool to add them
>> which is worse IMO.
>>
>
> If there is an expectation that one has to run the dtbTool as a post
> compilation thing, in my opinion its not a good idea.  But if that is
> the path that is decided (not my personal favourite) then we should
> at least let people know somehow that they have to run this tool in
> order to boot their kernel.   (dont like that either)
>
>
> Its already hard enough to get debug serial going, or figuring out how 
> to get serial debug out.  We should make it as easy as possible for 
> people that want to contribute and help.   Google did _NOT_ lock down 
> these phones on purpose so that people can do what they want with them 
> (within reason).  The fewer barriers to entry the better.
>
>
>
>> I'd also leave them undocumented as we want to minimize their usage.
>>
>
> I agree with this and will leave policing of their usage to RobH ;-)
>
> -jeremy
>
>
>> Rob
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