linux-kernel - Re: [EXT] Re: [PATCH v2 1/3] dt-bindings: usb: cdns-imx8qm: add imx8qm cdns3 glue bindings

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Message-ID: <48bdca7a-e4ec-a2e4-ff0d-dc9a08bf799e@linaro.org>
Date:   Tue, 21 Mar 2023 07:37:33 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Frank Li <frank.li@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>
Cc:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "festevam@...il.com" <festevam@...il.com>,
        "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Subject: Re: [EXT] Re: [PATCH v2 1/3] dt-bindings: usb: cdns-imx8qm: add
 imx8qm cdns3 glue bindings

On 20/03/2023 20:59, Frank Li wrote:
>>
>> The second is a good example - as you can see, there is a choice of
>> values, so they are not exactly fixed.
>>
>>>
>>> Such frequency information is necessary.  We can put to dts or clock drivers.
>> The clock driver
>>
>> If this is the argument, then the answer is NAK. Sorry, but DTS is not
>> for offloading fixed stuff just because you do not want to work on
>> drivers. The same for discoverable stuff.
>>
>>> Become bigger, or dts become bigger.  I think the key point is if property to
>> descript hardware information.
>>
>> You have to understand that with your binding you are not allowing to
>> any changes of these frequencies.
> 
> Do you means it should be okay if one of  clocks is not fixed?

We have here long discussion why does your binding require fixed
frequencies, because this is something unusual and not recommended. And
if they are really fixed, then device driver probably should make the
choice of frequencies.

> 
> Previous owner already left nxp.  I double checked our documents and scfw source code. 
> I miss understood a clock SC_PM_CLK_MST_BUS, which actually mapped to IP's aclk, which
> ware 100Mhz to 600Mhz. 
> 
>>
>> Best regards,
>> Krzysztof
> 

Best regards,
Krzysztof