linux-kernel - Re: [PATCH 2/6] dt-bindings: pinctrl: mt7620: add proper function muxing binding

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Date:   Wed, 14 Dec 2022 16:03:00 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sergio Paracuellos <sergio.paracuellos@...il.com>,
        Luiz Angelo Daros de Luca <luizluca@...il.com>
Cc:     linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org
Subject: Re: [PATCH 2/6] dt-bindings: pinctrl: mt7620: add proper function
 muxing binding

On 14.12.2022 14:55, Krzysztof Kozlowski wrote:
> On 13/12/2022 14:04, Arınç ÜNAL wrote:
>> Not every function can be muxed to a group. Add proper binding which
>> documents which function can be muxed to a group or set of groups.
>>
>> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
>> ---
>>   .../pinctrl/ralink,mt7620-pinctrl.yaml        | 632 +++++++++++++++++-
>>   1 file changed, 596 insertions(+), 36 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>> index 6f17f3991640..06880c80ba80 100644
>> --- a/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>> +++ b/Documentation/devicetree/bindings/pinctrl/ralink,mt7620-pinctrl.yaml
>> @@ -29,47 +29,608 @@ patternProperties:
>>           $ref: pinmux-node.yaml#
>>   
>>           properties:
>> -          groups:
>> -            description: The pin group to select.
>> -            enum: [
>> -              # common
>> -              i2c, spi, wdt,
>> -
>> -              # For MT7620 SoC
>> -              ephy, mdio, nd_sd, pa, pcie, rgmii1, rgmii2, spi refclk,
>> -              uartf, uartlite, wled,
>> -
>> -              # For MT7628 and MT7688 SoCs
>> -              gpio, i2s, p0led_an, p0led_kn, p1led_an, p1led_kn, p2led_an,
>> -              p2led_kn, p3led_an, p3led_kn, p4led_an, p4led_kn, perst, pwm0,
>> -              pwm1, refclk, sdmode, spi cs1, spis, uart0, uart1, uart2,
>> -              wled_an, wled_kn,
>> -            ]
>> -
>>             function:
>> -            description: The mux function to select.
>> -            enum: [
>> -              # common
>> -              gpio, i2c, refclk, spi,
>> -
>> -              # For MT7620 SoC
>> -              ephy, gpio i2s, gpio uartf, i2s uartf, mdio, nand, pa,
>> -              pcie refclk, pcie rst, pcm gpio, pcm i2s, pcm uartf,
>> -              rgmii1, rgmii2, sd, spi refclk, uartf, uartlite, wdt refclk,
>> -              wdt rst, wled,
>> -
>> -              # For MT7628 and MT7688 SoCs
>> -              antenna, debug, i2s, jtag, p0led_an, p0led_kn,
>> -              p1led_an, p1led_kn, p2led_an, p2led_kn, p3led_an, p3led_kn,
>> -              p4led_an, p4led_kn, pcie, pcm, perst, pwm, pwm0, pwm1, pwm_uart2,
>> -              rsvd, sdxc, sdxc d5 d4, sdxc d6, sdxc d7, spi cs1,
>> -              spis, sw_r, uart0, uart1, uart2, utif, wdt, wled_an, wled_kn, -,
>> -            ]
>> +            description:
>> +              A string containing the name of the function to mux to the group.
>> +            anyOf:
>> +              - description: For MT7620 SoC
>> +                enum: [ephy, gpio, gpio i2s, gpio uartf, i2c, i2s uartf, mdio, nand, pa,
>> +                       pcie refclk, pcie rst, pcm gpio, pcm i2s, pcm uartf, refclk,
>> +                       rgmii1, rgmii2, sd, spi, spi refclk, uartf, uartlite, wdt refclk,
>> +                       wdt rst, wled]
>> +
>> +              - description: For MT7628 and MT7688 SoCs
>> +                enum: [antenna, debug, gpio, i2c, i2s, jtag, p0led_an, p0led_kn,
>> +                       p1led_an, p1led_kn, p2led_an, p2led_kn, p3led_an, p3led_kn,
>> +                       p4led_an, p4led_kn, pcie, pcm, perst, pwm, pwm0, pwm1, pwm_uart2,
>> +                       refclk, rsvd, sdxc, sdxc d5 d4, sdxc d6, sdxc d7, spi, spi cs1,
>> +                       spis, sw_r, uart0, uart1, uart2, utif, wdt, wled_an, wled_kn, -]
>> +
>> +          groups:
>> +            description:
>> +              An array of strings. Each string contains the name of a group.
>>   
>>           required:
>>             - groups
>>             - function
>>   
>> +        allOf:
>> +          - if:
>> +              properties:
>> +                function:
>> +                  const: antenna
>> +            then:
>> +              properties:
>> +                groups:
>> +                  enum: [i2s]
> 
> I have doubts such setup is maintainable and readable. I would suggest
> to leave just few - maybe for gpio, jtag, refclk, utif.

These bindings are not going to change once all properly defined and I'm 
here as a maintainer so I don't see an issue with maintaining the binding.

It's the whole pin configuration of an SoC squashed under a single 
document. I guess this is the fate of the pinctrl bindings. The bindings 
for mt7622 is not so different:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pinctrl/mediatek%2Cmt7622-pinctrl.yaml#n63

It's still much better than reading the code:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pinctrl/ralink/pinctrl-mt7620.c

Arınç