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

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Date:   Tue, 15 Nov 2022 08:59:48 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Alex Elder <elder@...e.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 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.


Best regards,
Krzysztof