linux-kernel - Re: [PATCH v6 13/52] dt-bindings: memory: tegra124: emc: Document new interconnect property

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Message-ID: <f38984b6-d53f-a43d-0387-e787b3c1924d@gmail.com>
Date:   Tue, 27 Oct 2020 22:19:28 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>,
        Viresh Kumar <vireshk@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v6 13/52] dt-bindings: memory: tegra124: emc: Document new
 interconnect property

27.10.2020 13:25, Krzysztof Kozlowski пишет:
> On Mon, Oct 26, 2020 at 01:16:56AM +0300, Dmitry Osipenko wrote:
>> External memory controller is interconnected with memory controller and
>> with external memory. Document new interconnect property which turns
>> External Memory Controller into interconnect provider.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  .../bindings/memory-controllers/nvidia,tegra124-emc.yaml   | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml
>> index 278549f9e051..ac00832ceac1 100644
>> --- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml
>> +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra124-emc.yaml
>> @@ -29,6 +29,9 @@ properties:
>>      items:
>>        - const: emc
>>  
>> +  "#interconnect-cells":
>> +    const: 0
>> +
>>    nvidia,memory-controller:
>>      $ref: /schemas/types.yaml#/definitions/phandle
>>      description:
>> @@ -327,6 +330,7 @@ required:
>>    - clocks
>>    - clock-names
>>    - nvidia,memory-controller
>> +  - "#interconnect-cells"
> 
> Another required property, what about all existing users of this binding?

EMC/devfreq drivers check presence of the new properties and ask users
to upgrade the DT. The kernel will continue to work fine using older
DTBs, but devfreq driver won't load.

>>  additionalProperties: false
>>  
>> @@ -345,6 +349,7 @@ examples:
>>  
>>          #iommu-cells = <1>;
>>          #reset-cells = <1>;
>> +        #interconnect-cells = <1>;
> 
> You meant '0'?

'1' is for the "mc" node in the example (not "emc" node).

Anyways, I'll move this hunk to the previous patch in order to fix the
kernel bot warning.