linux-kernel - Re: [PATCH v3 1/3] dt-bindings: reserved-memory: rmtfs: Make qcom,vmid an array

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Message-ID: <118e34d1-617e-3d95-c31b-73b99109fc40@linaro.org>
Date:   Mon, 9 Jan 2023 13:13:53 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org
Cc:     marijn.suijten@...ainline.org, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] dt-bindings: reserved-memory: rmtfs: Make
 qcom,vmid an array

On 09/01/2023 12:41, Konrad Dybcio wrote:
> 
> 
> On 9.01.2023 10:51, Krzysztof Kozlowski wrote:
>> On 09/01/2023 10:39, Konrad Dybcio wrote:
>>> Some SoCs mandate that the RMTFS is also assigned to the NAV VM, while
>>> others really don't want that. Since it has to be conditional, turn
>>> qcom,vmid into an u32 array so that we can handle the NAV case, as
>>> well as other similar ones if they pop up in the future.
>>>
>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>>> ---
>>> v2 -> v3:
>>> Rewrite to accomodate for changes, don't pick up tags
>>>
>>>  .../devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml   | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml
>>> index 2998f1c8f0db..cfc2fda30eba 100644
>>> --- a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml
>>> +++ b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml
>>> @@ -27,9 +27,9 @@ properties:
>>>        identifier of the client to use this region for buffers
>>>  
>>>    qcom,vmid:
>>> -    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>>>      description: >
>>> -      vmid of the remote processor, to set up memory protection
>>> +      Array of vmids of the remote processors, to set up memory protection
>>
>> You need now min and maxItems.
> Hm, I tested it with and without:
> 
> minItems: 1
> maxItems: 2
> 
> on DTs with either one or two VMIDs defined and neither complains..

You can also make a property like:

	qcom,vmid: true

which will accept anything but it won't be correct approach. Properties
should have some reasonable constraints. Otherwise binding is not really
specific and is describing the interface in a very relaxed way.

Best regards,
Krzysztof