linux-kernel - Re: [PATCH 3/5] dt-bindings: mmc: sdhci-cadence: SD6 support

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Message-ID: <f9d4c883-4b76-c95e-c6dc-a659b4410bf2@linaro.org>
Date:   Sat, 7 Jan 2023 14:25:02 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Piyush Malgujar <pmalgujar@...vell.com>
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        adrian.hunter@...el.com, ulf.hansson@...aro.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        yamada.masahiro@...ionext.com, devicetree@...r.kernel.org,
        jannadurai@...vell.com, cchavva@...vell.com
Subject: Re: [PATCH 3/5] dt-bindings: mmc: sdhci-cadence: SD6 support

On 06/01/2023 17:48, Piyush Malgujar wrote:
> Hi Krzysztof,
> 
> Thank you the review comments.
> 
> On Mon, Dec 19, 2022 at 04:40:35PM +0100, Krzysztof Kozlowski wrote:
>> On 19/12/2022 15:24, Piyush Malgujar wrote:
>>> From: Jayanthi Annadurai <jannadurai@...vell.com>
>>>
>>
>> Subject: use final prefix matching the file, so "cdns,sdhci:"
>>
>>> Add support for SD6 controller support
>>
>> Full stop.
>>
>>>
>>> Signed-off-by: Jayanthi Annadurai <jannadurai@...vell.com>
>>> Signed-off-by: Piyush Malgujar <pmalgujar@...vell.com>
>>> ---
>>>  .../devicetree/bindings/mmc/cdns,sdhci.yaml   | 33 +++++++++++++++++--
>>>  1 file changed, 31 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml b/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
>>> index 8b1a0fdcb5e3e2e8b87d8d7678e37f3dad447fc1..2043e78ccd5f708a01e87fd96ec410418fcd539f 100644
>>> --- a/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
>>> +++ b/Documentation/devicetree/bindings/mmc/cdns,sdhci.yaml
>>> @@ -4,7 +4,7 @@
>>>  $id: http://devicetree.org/schemas/mmc/cdns,sdhci.yaml#
>>>  $schema: http://devicetree.org/meta-schemas/core.yaml#
>>>  
>>> -title: Cadence SD/SDIO/eMMC Host Controller (SD4HC)
>>> +title: Cadence SD/SDIO/eMMC Host Controller (SD4HC, SD6HC)
>>>  
>>>  maintainers:
>>>    - Masahiro Yamada <yamada.masahiro@...ionext.com>
>>> @@ -19,6 +19,7 @@ properties:
>>>            - microchip,mpfs-sd4hc
>>>            - socionext,uniphier-sd4hc
>>>        - const: cdns,sd4hc
>>> +      - const: cdns,sd6hc
>>
>> Does not look like you tested the DTS against bindings. Please run `make
>> dtbs_check` (see Documentation/devicetree/bindings/writing-schema.rst
>> for instructions).
>>
>> ... because it does not really make sense. Why do you require SD6HC as
>> fallback? I think you meant enum.
>>
> 
> Yes, that's correct. I will change it to enum.
> 
>>>  
>>>    reg:
>>>      maxItems: 1
>>> @@ -111,6 +112,34 @@ properties:
>>>      minimum: 0
>>>      maximum: 0x7f
>>>  
>>> +  cdns,iocell_input_delay:
>>
>> No underscores. Use proper units in name suffix:
>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
>>
>>
>>> +    description: Delay in ps across the input IO cells
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>
>> Ditto... and so on - all of the fields.
>>
>>> +
>>> +  cdns,iocell_output_delay:
>>> +    description: Delay in ps across the output IO cells
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>> +
>>> +  cdns,delay_element:
>>> +    description: Delay element in ps used for calculating phy timings
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>> +
>>> +  cdns,read_dqs_cmd_delay:
>>> +    description: Command delay used in HS200 tuning
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>> +
>>> +  cdns,tune_val_start:
>>> +    description: Staring value of data delay used in HS200 tuning
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>> +
>>> +  cdns,tune_val_step:
>>> +    description: Incremental value of data delay used in HS200 tuning
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>> +
>>> +  cdns,max_tune_iter:
>>> +    description: Maximum number of iterations to complete the HS200 tuning process
>>> +    $ref: "/schemas/types.yaml#/definitions/uint32"
>>
>> Why these three are properties of DT?
>>
> 
> These tuning parameters are added here so to make them custom configurable for different
> boards.

I understand why do you wanted to add them, but I am asking why these
are suitable for DT? DT  describes hardware, so what is here specific to
hardware which requires DT property?


Best regards,
Krzysztof