linux-kernel - Re: [PATCH net-next 1/5] dt-bindings: net: qcom,ipa: deprecate modem-init

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Message-ID: <48fbae83-728e-d7ec-7516-4f8c972a1a1d@ieee.org>
Date:   Tue, 15 Nov 2022 03:00:31 -0600
From:   Alex Elder <elder@...e.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alex Elder <elder@...aro.org>, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Cc:     andersson@...nel.org, konrad.dybcio@...aro.org, agross@...nel.org,
        elder@...nel.org, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/5] dt-bindings: net: qcom,ipa: deprecate
 modem-init

On 11/15/22 01:59, Krzysztof Kozlowski wrote:
> On 14/11/2022 18:48, Alex Elder wrote:
>> On 11/14/22 03:56, Krzysztof Kozlowski wrote:
>>> On 12/11/2022 21:07, Alex Elder wrote:
>>>> GSI firmware for IPA must be loaded during initialization, either by
>>>> the AP or by the modem.  The loader is currently specified based on
>>>> whether the Boolean modem-init property is present.
>>>>
>>>> Instead, use a new property with an enumerated value to indicate
>>>> explicitly how GSI firmware gets loaded.  With this in place, a
>>>> third approach can be added in an upcoming patch.
>>>>
>>>> The new qcom,gsi-loader property has two defined values:
>>>>     - self:   The AP loads GSI firmware
>>>>     - modem:  The modem loads GSI firmware
>>>> The modem-init property must still be supported, but is now marked
>>>> deprecated.
>>>>
>>>> Signed-off-by: Alex Elder <elder@...aro.org>
>>>> ---
>>>>    .../devicetree/bindings/net/qcom,ipa.yaml     | 59 +++++++++++++++----
>>>>    1 file changed, 46 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/net/qcom,ipa.yaml b/Documentation/devicetree/bindings/net/qcom,ipa.yaml
>>>> index e752b76192df0..0dfd6c721e045 100644
>>>> --- a/Documentation/devicetree/bindings/net/qcom,ipa.yaml
>>>> +++ b/Documentation/devicetree/bindings/net/qcom,ipa.yaml
>>>> @@ -124,12 +124,22 @@ properties:
>>>>          - const: ipa-clock-enabled-valid
>>>>          - const: ipa-clock-enabled
>>>>    
>>>> +  qcom,gsi-loader:
>>>> +    enum:
>>>> +      - self
>>>> +      - modem
>>>> +    description:
>>>> +      This indicates how GSI firmware should be loaded.  If the AP loads
>>>
>>> s/This indicates/Indicate/
>>> (or any other grammar without describing DT syntax but hardware/system)
>>
>> OK.
>>
>>>> +      and validates GSI firmware, this property has value "self".  If the
>>>> +      modem does this, this property has value "modem".
>>>> +
>>>>      modem-init:
>>>> +    deprecated: true
>>>>        type: boolean
>>>>        description:
>>>> -      If present, it indicates that the modem is responsible for
>>>> -      performing early IPA initialization, including loading and
>>>> -      validating firwmare used by the GSI.
>>>> +      This is the older (deprecated) way of indicating how GSI firmware
>>>> +      should be loaded.  If present, the modem loads GSI firmware; if
>>>> +      absent, the AP loads GSI firmware.
>>>>    
>>>>      memory-region:
>>>>        maxItems: 1
>>>> @@ -155,15 +165,36 @@ required:
>>>>      - interconnects
>>>>      - qcom,smem-states
>>>>    
>>>> -# If modem-init is not present, the AP loads GSI firmware, and
>>>> -# memory-region must be specified
>>>> -if:
>>>> -  not:
>>>> -    required:
>>>> -      - modem-init
>>>> -then:
>>>> -  required:
>>>> -    - memory-region
>>>> +allOf:
>>>> +  # If qcom,gsi-loader is present, modem-init must not be present
>>>> +  - if:
>>>> +      required:
>>>> +        - qcom,gsi-loader
>>>> +    then:
>>>> +      properties:
>>>> +        modem-init: false
>>>
>>> This is ok, but will not allow you to keep deprecated property in DTS
>>> for the transition period. We talked about this that you need to keep
>>> both or wait few cycles before applying DTS cleanups.
>>
>> My intention is expressed in the comment.  Is it because of the
>> "if .... required ... qcom,gsi-loader"?
>>
>> Should it be "if ... properties ... qcom,gsi-loader"?
> 
> You disallow modem-init here, so it cannot be present in DTS if
> gsi-loader is present. Therefore the deprecated case like this:
>    qcom,gsi-loader = "modem"
>    modem-init;
> is not allowed by the schema.
> 
> As I said, it is fine, but your DTS should wait a cycle.

OK, then this is exactly as I intended.  I am planning to wait
until Linux v6.2-rc1 is published before I post the DTS updates
that implement this change.  It is not technically necessary
until IPA v5.0 is fully supported, and I don't have confidence
all of that will accepted before then.

If I did it "your way" first I could get it done now, but then
I'd want to do another round later to make it this way.

I will still send an updated series shortly, to address your
other comment about wording in the description.  But I will
not be changing this part.

Thanks for the explanation Krzysztof.

					-Alex


> 
> 
> Best regards,
> Krzysztof
>