Re: [EXT] Re: [PATCH v3 1/3] dt-bindings: usb: cdns-imx8qm: add imx8qm cdns3 glue bindings

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 22/03/2023 23:15, Frank Li wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> Sent: Wednesday, March 22, 2023 5:09 PM
>> To: Frank Li <frank.li@nxp.com>
>> Cc: devicetree@vger.kernel.org; festevam@gmail.com; imx@lists.linux.dev;
>> kernel@pengutronix.de; krzysztof.kozlowski+dt@linaro.org; linux-arm-
>> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>; linux-
>> kernel@vger.kernel.org; robh+dt@kernel.org; s.hauer@pengutronix.de;
>> shawnguo@kernel.org
>> Subject: Re: [EXT] Re: [PATCH v3 1/3] dt-bindings: usb: cdns-imx8qm: add
>> imx8qm cdns3 glue bindings
>>
>> Caution: EXT Email
>>
>> On 22/03/2023 22:57, Frank Li wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Sent: Wednesday, March 22, 2023 4:43 PM
>>>> To: Frank Li <frank.li@nxp.com>
>>>> Cc: devicetree@vger.kernel.org; festevam@gmail.com;
>> imx@lists.linux.dev;
>>>> kernel@pengutronix.de; krzysztof.kozlowski+dt@linaro.org; linux-arm-
>>>> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>; linux-
>>>> kernel@vger.kernel.org; robh+dt@kernel.org; s.hauer@pengutronix.de;
>>>> shawnguo@kernel.org
>>>> Subject: Re: [EXT] Re: [PATCH v3 1/3] dt-bindings: usb: cdns-imx8qm: add
>>>> imx8qm cdns3 glue bindings
>>>>
>>>> Caution: EXT Email
>>>>
>>>> On 22/03/2023 22:40, Frank Li wrote:
>>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>>>> Sent: Wednesday, March 22, 2023 4:38 PM
>>>>>> To: Frank Li <frank.li@nxp.com>
>>>>>> Cc: devicetree@vger.kernel.org; festevam@gmail.com;
>>>> imx@lists.linux.dev;
>>>>>> kernel@pengutronix.de; krzysztof.kozlowski+dt@linaro.org; linux-arm-
>>>>>> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>; linux-
>>>>>> kernel@vger.kernel.org; robh+dt@kernel.org;
>> s.hauer@pengutronix.de;
>>>>>> shawnguo@kernel.org
>>>>>> Subject: Re: [EXT] Re: [PATCH v3 1/3] dt-bindings: usb: cdns-imx8qm:
>> add
>>>>>> imx8qm cdns3 glue bindings
>>>>>>
>>>>>> Caution: EXT Email
>>>>>>
>>>>>> On 22/03/2023 22:36, Frank Li wrote:
>>>>>>>
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>>>>>> Sent: Wednesday, March 22, 2023 4:32 PM
>>>>>>>> To: Frank Li <frank.li@nxp.com>
>>>>>>>> Cc: devicetree@vger.kernel.org; festevam@gmail.com;
>>>>>> imx@lists.linux.dev;
>>>>>>>> kernel@pengutronix.de; krzysztof.kozlowski+dt@linaro.org; linux-
>> arm-
>>>>>>>> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>;
>> linux-
>>>>>>>> kernel@vger.kernel.org; robh+dt@kernel.org;
>>>> s.hauer@pengutronix.de;
>>>>>>>> shawnguo@kernel.org
>>>>>>>> Subject: Re: [EXT] Re: [PATCH v3 1/3] dt-bindings: usb: cdns-imx8qm:
>>>> add
>>>>>>>> imx8qm cdns3 glue bindings
>>>>>>>>
>>>>>>>> Caution: EXT Email
>>>>>>>>
>>>>>>>> On 22/03/2023 15:34, Frank Li wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>>>>>>>> Sent: Wednesday, March 22, 2023 2:32 AM
>>>>>>>>>> To: Frank Li <frank.li@nxp.
>>>>>>>>>>> +      - const: usb3_aclk
>>>>>>>>>>> +      - const: usb3_ipg_clk
>>>>>>>>>>> +      - const: usb3_core_pclk
>>>>>>>>>>> +
>>>>>>>>>>> +  assigned-clocks:
>>>>>>>>>>> +    items:
>>>>>>>>>>> +      - description: Phandle and clock specifoer of
>>>>>>>>>> IMX_SC_PM_CLK_MST_BUS.
>>>>>>>>>>
>>>>>>>>>> Drop useless pieces so "Phandle and clock specifoer of " and
>> name
>>>> the
>>>>>>>>>> hardware, not the syntax.
>>>>>>>>>>
>>>>>>>>>>> +
>>>>>>>>>>> +  assigned-clock-rates:
>>>>>>>>>>> +    items:
>>>>>>>>>>> +      - description: Should be in Range 100 - 600 Mhz.
>>>>>>>>>>
>>>>>>>>>> That's better but I still do not understand why do you need it in
>> the
>>>>>>>>>> bindings. You never actually answered this question.
>>>>>>>>>
>>>>>>>>> I am not sure 100% sure the reason.
>>>>>>>>> I think difference system target's  axi bus frequency is difference,
>>>>>>>>> And just one time work, needn't software to manage it.
>>>>>>>>> Following other driver's code style may be another reason.
>>>>>>>>
>>>>>>>> That's the reason of heaving it in DTS. But I am asking about bindings.
>>>>>>>> You do understand you define here interface?
>>>>>>>
>>>>>>> I defined here is descript AXI frequency for usb controller. Supposed
>>>>>> difference
>>>>>>> Platform will have difference working frequency.
>>>>>>
>>>>>> I don't understand how does this answer my concerns of having it in DT
>>>>>> bindings. If you do not add it, you "will have difference working
>>>>>> frequency", so what's the point?
>>>>>
>>>>> For example: imx8qxp, it need set to 250Mhz,  i.MX8QM need set to
>>>> 200Mhz.
>>>>> Maybe future chip can set to 400Mhz.
>>>>
>>>> And? So as you can see you will still have different frequencies, so
>>>> what's the point? What is the benefit? Dunno, maybe we do not
>> understand
>>>> each other, because I don't think you are answering my questions at all.
>>>
>>> Benefit: New chip just need change dts file for the same IP, like change
>> base
>>> Reg address and irq number.
>>
>> To remind - the question was:
>> "That's better but I still do not understand why do you need it in the
>> bindings."
>> If you drop it from the bindings the benefit is still there, so what do
>> you want to prove?
>>
>>>
>>> Your question is:  "why need this assigned-clock-rates
>> IMX_SC_PM_CLK_MST_BUS property?"
>>
>> This was the previous thread. Now, related but slightly different, why
>> do you still need it in the bindings?
>>
>>
>>> My answer: it is one of hardware property, like reg base address and irq
>> number.
>>
>> Sure, it is, I know, and bindings already allow it. Just look at many
>> DTS and their bindings. Do you see the bindings defining this property?
>> No. So why do you think it is needed here? I am asking this since like 6
>> emails and your answers are not related to bindings at all.
>>
>>>
>>> If can't match your expectation, can you change another words or provide
>> me an example?
>>
>> Yeah, just open several DTS and look for assigned-clock, then open their
>> bindings and answer - why do you need to add it to the binding but all
>> other bindings did not have to? If you have the answer, sure, bring
>> these parts of bindings.
> 
> Do you means, Needn't add assigned-clock in binding *document* yaml file?
> And dts file still can use assigned-clock property. 

Yes, I said it many times already...

Best regards,
Krzysztof