Re: [PATCH v2 00/07] ARM: shmobile: APMU DT support via SMP Enable method V2

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Hi Simon,

On Tue, Aug 25, 2015 at 9:49 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
> Hi Magnus,
>
> On Sun, Aug 23, 2015 at 04:24:27PM +0900, Magnus Damm wrote:
>> ARM: shmobile: APMU DT support via SMP Enable method V2
>>
>> [PATCH v2 01/07] devicetree: bindings: Renesas APMU and SMP Enable method
>> [PATCH v2 02/07] ARM: shmobile: Add APMU DT support via Enable method
>> [PATCH v2 03/07] ARM: shmobile: Add APMU nodes to r8a7790 DTSI
>> [PATCH v2 04/07] ARM: shmobile: Add APMU nodes to r8a7791 DTSI
>> [PATCH v2 05/07] ARM: shmobile: Add function to prioritize DT SMP
>> [PATCH v2 06/07] ARM: shmobile: Prioritize r8a7790 DT APMU support
>> [PATCH v2 07/07] ARM: shmobile: Prioritize r8a7791 DT APMU support
>>
>> These patches add DT support for the APMU hardware commonly found in
>> Renesas R-Car Gen2 SoCs. Without these patches the APMU gets configured
>> through data expressed in C, and with this series applied it is possible
>> to describe the APMU configuration in DT and let the enable method point
>> out that the APMU should be used.
>>
>> Patch 1 and 2 are Documenting and adding DT support to the APMU driver
>> together with enabling use of the enable-method way to describe that
>> the APMU hardware is needed for SMP operation.
>>
>> Patch 3 and 4 are related to r8a7790/r8a7791 support that get a DTSI update
>> to describe the APMU hardware. To avoid breaking support for older DTBs out
>> in the wild these patches keep the older existing C code APMU configuration
>> as-is. Patch 5-7 make sure that during run-time, if the APMU is installed
>> via the DT enable-method then it will not be overriden by older non-DT
>> configuration.
>>
>> I suggest making APMU DT configuration mandatory for SMP operation on
>> newer SoCs and that we keep the old APMU support code in place for a
>> good number of kernel releases or until we can identify a couple of major
>> reasons good enough to force a DTB update on the end users.
>>
>> In the future r8a7793 and r8a7794 support may be added by using code
>> similar to patch 3 and 4 but without any C-based SMP code and fallback.
>
> Sounds reasonable.
>
> Looking over the review of this series I see only one minor comment
> regarding spelling in documentation. I have it in mind to queue up
> this series with that problem fixed unless objections are raised
> in the near future. Please feel free to convince me otherwise or
> repost the series with the spelling error fixed.

Thanks for your feedback! My plan is to update this series once more
early next month, so no need to pick anything up right now.

I feel that we should discuss with the ARM SoC guys about the reason
why SMP Enable DT binding is needed. From my side it seems enough to
determine the SMP configuration from the SoC part number (and maybe
APMU DT bits) that we already have encoded in DT.

Perhaps discussing that at ELCE would be good?

Best,

/ magnus
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