Re: [PATCH v6 05/52] dt-bindings: memory: tegra20: mc: Document new interconnect property

Dmitry Osipenko
2020-10-27T19:22:24Z

27.10.2020 11:55, Krzysztof Kozlowski пишет:
> On Mon, Oct 26, 2020 at 01:16:48AM +0300, Dmitry Osipenko wrote:
>> Memory controller is interconnected with memory clients and with the
>> External Memory Controller. Document new interconnect property which
>> turns memory controller into interconnect provider.
>>
>> Acked-by: Rob Herring <robh@kernel.org>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>> .../bindings/memory-controllers/nvidia,tegra20-mc.txt | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-mc.txt b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-mc.txt
>> index e55328237df4..739b7c6f2e26 100644
>> --- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-mc.txt
>> +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-mc.txt
>> @@ -16,6 +16,8 @@ Required properties:
>> IOMMU specifier needed to encode an address. GART supports only a single
>> address space that is shared by all devices, therefore no additional
>> information needed for the address encoding.
>> +- #interconnect-cells : Should be 1. This cell represents memory client.
>> + The assignments may be found in header file <dt-bindings/memory/tegra20-mc.h>.
>
> This is a list of required properties so you break the ABI. All existing
> DTBs will be affected.

This is optional property for the older DTBs, but for newer DTs it's
mandatory. IIUC, it should be defined as a required property in the
binding.

Please see tegra_mc_interconnect_setup() in "memory: tegra-mc: Add
interconnect framework", which check presence of the ICC DT property.