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

[Frank Li]

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski at linaro.org>
> Sent: Wednesday, March 22, 2023 5:09 PM
> To: Frank Li <frank.li at nxp.com>
> Cc: devicetree at vger.kernel.org; festevam at gmail.com; imx at lists.linux.dev;
> kernel at pengutronix.de; krzysztof.kozlowski+dt at linaro.org; linux-arm-
> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>; linux-
> kernel at vger.kernel.org; robh+dt at kernel.org; s.hauer at pengutronix.de;
> shawnguo at 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 at linaro.org>
> >> Sent: Wednesday, March 22, 2023 4:43 PM
> >> To: Frank Li <frank.li at nxp.com>
> >> Cc: devicetree at vger.kernel.org; festevam at gmail.com;
> imx at lists.linux.dev;
> >> kernel at pengutronix.de; krzysztof.kozlowski+dt at linaro.org; linux-arm-
> >> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>; linux-
> >> kernel at vger.kernel.org; robh+dt at kernel.org; s.hauer at pengutronix.de;
> >> shawnguo at 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 at linaro.org>
> >>>> Sent: Wednesday, March 22, 2023 4:38 PM
> >>>> To: Frank Li <frank.li at nxp.com>
> >>>> Cc: devicetree at vger.kernel.org; festevam at gmail.com;
> >> imx at lists.linux.dev;
> >>>> kernel at pengutronix.de; krzysztof.kozlowski+dt at linaro.org; linux-arm-
> >>>> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>; linux-
> >>>> kernel at vger.kernel.org; robh+dt at kernel.org;
> s.hauer at pengutronix.de;
> >>>> shawnguo at 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 at linaro.org>
> >>>>>> Sent: Wednesday, March 22, 2023 4:32 PM
> >>>>>> To: Frank Li <frank.li at nxp.com>
> >>>>>> Cc: devicetree at vger.kernel.org; festevam at gmail.com;
> >>>> imx at lists.linux.dev;
> >>>>>> kernel at pengutronix.de; krzysztof.kozlowski+dt at linaro.org; linux-
> arm-
> >>>>>> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>;
> linux-
> >>>>>> kernel at vger.kernel.org; robh+dt at kernel.org;
> >> s.hauer at pengutronix.de;
> >>>>>> shawnguo at 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 at linaro.org>
> >>>>>>>> Sent: Wednesday, March 22, 2023 2:32 AM
> >>>>>>>> To: Frank Li <frank.li at 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. 

> 
> Best regards,
> Krzysztof