Re: [PATCH v3 07/11] dt-bindings: clock: Add StarFive JH7110 system clock and reset generator

Krzysztof Kozlowski
2023-02-18T14:55:35Z

On 18/02/2023 12:17, Conor Dooley wrote:
> Hey Krzysztof,
>
> On Sat, Feb 18, 2023 at 11:20:30AM +0100, Krzysztof Kozlowski wrote:
>> On 17/02/2023 17:27, Conor Dooley wrote:
>>> On Fri, Feb 17, 2023 at 04:47:48PM +0100, Krzysztof Kozlowski wrote:
>>>> On 17/02/2023 14:32, Conor Dooley wrote:
>>>>>>>> Yes, it is.
>>>>>>>
>>>>>>> Which would then make GMAC1 RGMII RX optional, rather than required?
>>>>>>
>>>>>> If thinking in this way, I must say yes, it is optional. But actually
>>>>>> GMAC1 RGMII RX feeds gmac1_rx by default.
>>>>>> For a mux, it usually works if you populate only one input to it.
>>>>>> Does it mean all the other inputs are optional? And how can we define
>>>>>> which input is required?
>>>>>
>>>>> I'm not sure, that is a question for Krzysztof and/or Rob.
>>>>
>>>> That's a long thread, please summarize what you ask. Otherwise I have no
>>>> clue what is the question.
>>>
>>> Sorry. I tried to preserve the context of the conversation the last time
>>> I cropped it so that things would be contained on one email.
>>>
>>> For me at least, I am wondering how you convey that out of a list of
>>> clock inputs (for example a, b, c, d) that two of the clocks are inputs
>>> to a mux and it is only required to provide one of the two (say b & c).
>
> You skipped this part which was what I was trying to ask you about.

Yeah, I skipped a lot because there was one big thread with a question:
what do you think? Sorry, I will not dig 8 emails thread to figure out
which question is to me and which is not...

> Do you know how to convey this situation, or is it even possible to
> express those rules?

oneOf:
- clock-names:
minItems: 3
items:
- a
- b
- c
- d
- clock-names:
items:
- a
- b
- d

or maybe:
- clock-names:
minItems: 3
items:
- a
- b
- enum: [c, d]
- d

>
>>>> Does the mux works correctly if clock input is not connected? I mean,
>>>> are you now talking about real hardware or some simplification from SW
>>>> point of view?
>>>
>>> I'm coming at this from an angle of "is a StarFive customer going to show
>>> up with a devicetree containing dummy fixed-clocks to satisfy dtbs_check
>>> because they opted to only populate one input to the mux".
>>> I don't really care about implications for the driver, just about
>>> whether the hardware allows for inputs to the mux to be left
>>> un-populated.
>>
>> Whether hardware allows - not a question to me.
>
>> BTW, this is rather question coming from me...
>
> I don't understand what you mean by this, sorry.

You said to a letter addressed to me "whether the hardware allows for
...". Why would you ask me about hardware I know nothing about? That was
my question - I am asking - whether hardware allows it or not. Then
write bindings depending on that.

Best regards,
Krzysztof