Re: [PATCH v4 2/3] dt-bindings: fpga: xlnx,fpga-selectmap: add DT schema

[Charles Perry <charles.perry@savoirfairelinux.com>]

On Mar 4, 2024, at 12:31 AM, Krzysztof Kozlowski krzysztof.kozlowski@linaro.org wrote:

> On 04/03/2024 08:30, Krzysztof Kozlowski wrote:
>> On 03/03/2024 18:21, Charles Perry wrote:
>>> On Feb 27, 2024, at 3:10 AM, Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
>>> wrote:
>>>
>>>> On 21/02/2024 20:50, Charles Perry wrote:
>>>>> Document the SelectMAP interface of Xilinx 7 series FPGA.
>>>>>
>>>>> Signed-off-by: Charles Perry <charles.perry@savoirfairelinux.com>
>>>>> ---
>>>>>  .../bindings/fpga/xlnx,fpga-selectmap.yaml    | 86 +++++++++++++++++++
>>>>>  1 file changed, 86 insertions(+)
>>>>>  create mode 100644
>>>>>  Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml
>>>>> b/Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml
>>>>> new file mode 100644
>>>>> index 0000000000000..08a5e92781657
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml
>>>>> @@ -0,0 +1,86 @@
>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>> +%YAML 1.2
>>>>> +---
>>>>> +$id: http://devicetree.org/schemas/fpga/xlnx,fpga-selectmap.yaml#
>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>> +
>>>>> +title: Xilinx SelectMAP FPGA interface
>>>>> +
>>>>> +maintainers:
>>>>> +  - Charles Perry <charles.perry@savoirfairelinux.com>
>>>>> +
>>>>> +description: |
>>>>> +  Xilinx 7 Series FPGAs support a method of loading the bitstream over a
>>>>> +  parallel port named the SelectMAP interface in the documentation. Only
>>>>> +  the x8 mode is supported where data is loaded at one byte per rising edge of
>>>>> +  the clock, with the MSB of each byte presented to the D0 pin.
>>>>> +
>>>>> +  Datasheets:
>>>>> +
>>>>> https://www.xilinx.com/support/documentation/user_guides/ug470_7Series_Config.pdf
>>>>> +
>>>>> +allOf:
>>>>> +  - $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
>>>>> +
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    enum:
>>>>> +      - xlnx,fpga-xc7s-selectmap
>>>>> +      - xlnx,fpga-xc7a-selectmap
>>>>> +      - xlnx,fpga-xc7k-selectmap
>>>>> +      - xlnx,fpga-xc7v-selectmap
>>>>> +
>>>>> +  reg:
>>>>> +    description:
>>>>> +      At least 1 byte of memory mapped IO
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  prog_b-gpios:
>>>>
>>>> I commented on this and still see underscore. Nothing in commit msg
>>>> explains why this should have underscore. Changelog is also vague -
>>>> describes that you brought back underscores, instead of explaining why
>>>> you did it.
>>>>
>>>> So the same comments as usual:
>>>>
>>>> No underscores in names.
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>
>>> Hello Krzysztof,
>>>
>>> Yes, I've gone full circle on that issue. Here's what I tried so far:
>> 
>> And what part of the commit description allows me to understand this?
>> 

I have a changelog in the cover letter:
https://lore.kernel.org/all/20240221195058.1281973-1-charles.perry@savoirfairelinux.com/

>>>
>>>  1) Reuse the same gpio names: Duplicates errors of the past, Krzysztof
>>>     doesn't like it.
>>>  2) Different gpio names for new driver only: Makes the driver code
>>>     overly complicated, Yilun doesn't like it.
>> 
>> That's a new driver, right? So what is complicated here? You have new
>> code and you take prog-b or prog_b?
>> 
>>>  3) Change gpio names for both drivers, deprecate the old names: Makes
>>>     the DT binding and the driver code overly complicated, Rob doesn't
>>>     like it.
>> 
>> I don't think I proposed changing existing bindings.
>> 
>>>
>>> I think that while the driver code shouldn't be the driving force for
>>> the DT spec, it can be a good indication that the spec is unpractical to
>>> implement.
>> 
>> What is impractical in implementing this? You just pass either A or B to
>> function requesting GPIO. Just choose proper name.
>>

It's not complicated but it requires more code than if "prog_b" had been
used. 
 
>>>
>>> In this case, there are two interfaces on a chip that uses the same GPIO
>>> protocol, it would only make sense that they use the same names, this
>>> discards solution #2.
>> 
>> I don't understand this. You have devm_gpiod_get() in your new code. Why
>> is it difficult to use different name?

Yilun asked to avoid changing the names between the two drivers.
First comment in this mail:
https://lore.kernel.org/all/Zb9GkY6cMtR+4xOX@yilunxu-OptiPlex-7050/

Yilun, let me know if this is something you'd accept as this is a concern
for the device tree maintainers.

> 
> And I forgot to emphasize: none of these is mentioned in commit msg, so
> for v5 you will get exactly the same complains. And for every other
> patch which repeats the same and does not clarify caveats or exceptions.
> 
> Best regards,
> Krzysztof

Should I keep my changelog in the individual commits? I thought the norm
was to put this the cover letter.

Regards,
Charles