linux-kernel - Re: [PATCH v2 1/5] dt-bindings: pinctrl: Add StarFive JH7110 pinctrl definitions

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Message-ID: <8677051a-604a-210c-066c-75db444d6f09@starfivetech.com>
Date:   Tue, 29 Nov 2022 23:58:30 +0800
From:   Jianlong Huang <jianlong.huang@...rfivetech.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Hal Feng <hal.feng@...rfivetech.com>,
        <linux-riscv@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>
CC:     Conor Dooley <conor@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        "Rob Herring" <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Emil Renner Berthing <emil.renner.berthing@...onical.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/5] dt-bindings: pinctrl: Add StarFive JH7110 pinctrl
 definitions

On Tue, 29 Nov 2022 15:58:12 +0100, Krzysztof Kozlowski wrote:
> On 29/11/2022 15:46, Jianlong Huang wrote:
>> On Tue, 29 Nov 2022 08:49:49 +0100, Krzysztof Kozlowski wrote:
>>> On 29/11/2022 02:47, Jianlong Huang wrote:
>>>> On Mon, 28 Nov 2022 09:32:45 +0100, Krzysztof Kozlowski wrote:
>>>>> On 28/11/2022 01:48, Jianlong Huang wrote:
>>>>>
>>>>>>>>> +/* aon_iomux doen */
>>>>>>>>> +#define GPOEN_AON_PTC0_OE_N_4			2
>>>>>>>>> +#define GPOEN_AON_PTC0_OE_N_5			3
>>>>>>>>> +#define GPOEN_AON_PTC0_OE_N_6			4
>>>>>>>>> +#define GPOEN_AON_PTC0_OE_N_7			5
>>>>>>>>> +
>>>>>>>>
>>>>>>>> It looks like you add register constants to the bindings. Why? The
>>>>>>>> bindings are not the place to represent hardware programming model. Not
>>>>>>>> mentioning that there is no benefit in this.
>>>>>>>
>>>>>>> Also: this entire file should be dropped, but if it stays, you have to
>>>>>>> name it matching bindings or compatible (vendor,device.h).
>>>>>>
>>>>>> Thanks your comments.
>>>>>> These macros are used to configure pinctrl in dts, so the file should stay,
>>>>>
>>>>> Why they should stay? What's the reason? If it is not a constant used by
>>>>> driver, then register values should not be placed in the bindings, so
>>>>> drop it.
>>>>>
>>>>
>>>> Thanks.
>>>>
>>>> These macros in binding header(example, DOUT, DOEN etc) will be used in DTS,
>>>> and driver will parse the DT for pinctrl configuration.
>>>>
>>>> Example in dts:
>>>> uart0_pins: uart0-0 {
>>>> 	tx-pins {
>>>> 		pinmux = <GPIOMUX(5, GPOUT_SYS_UART0_TX, GPOEN_ENABLE, GPI_NONE)>;
>>>
>>> This is usage in DTS and is not an argument to store register
>>> addresses/offsets as bindings. What is the usage (of define, not value)
>>> in the driver?
>>>
>> 
>> The existing implementation reuse the macros for DTS and driver.
> 
> Where in the driver? Grep gives zero results.
> 
>> Do you mean we need to separate the macros, one for DTS and one for driver usage?
> 
> No, if driver uses them it is fine. The problem is I cannot find it
> anywhere.
> 
>> Or you have any better suggestion?
>> 
>> These macros are the value of register, not register addresses/offsets,
>> except for with prefix of GPI.
> 
> Still, values are not usually part of bindings.
> 
>> 
>> Drivers rarely reference macros directly, mostly parsing dts and writing them to registers.
> 
> So drivers do not use macros? Then there is no reason to store them in
> bindings? What do you "bind" if there is no usage (and we do not talk
> about DTS...)?
> 

Where do you suggest to store these macros used in DTS?

Best regards,
Jianlong Huang