linux-kernel - Re: [PATCH v2 3/9] includes: dt-bindings: Add STM32F429 pinctrl DT bindings

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Date:	Tue, 20 Oct 2015 18:32:36 +0200
From:	Maxime Coquelin <mcoquelin.stm32@...il.com>
To:	Daniel Thompson <daniel.thompson@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>
Cc:	Mark Rutland <mark.rutland@....com>,
	Rob Herring <robh+dt@...nel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andreas Färber <afaerber@...e.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Bruno Herrera <bruherrera@...il.com>
Subject: Re: [PATCH v2 3/9] includes: dt-bindings: Add STM32F429 pinctrl DT bindings

2015-10-20 12:06 GMT+02:00 Daniel Thompson <daniel.thompson@...aro.org>:
> On 17/10/15 18:23, Maxime Coquelin wrote:
>>
>> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@...il.com>
>> ---
>>   include/dt-bindings/pinctrl/pinctrl-stm32.h     |   12 +
>>   include/dt-bindings/pinctrl/stm32f429-pinfunc.h | 1241
>> +++++++++++++++++++++++
>>   2 files changed, 1253 insertions(+)
>>   create mode 100644 include/dt-bindings/pinctrl/pinctrl-stm32.h
>>   create mode 100644 include/dt-bindings/pinctrl/stm32f429-pinfunc.h
>>
>> diff --git a/include/dt-bindings/pinctrl/pinctrl-stm32.h
>> b/include/dt-bindings/pinctrl/pinctrl-stm32.h
>> new file mode 100644
>> index 0000000..a2e7222
>> --- /dev/null
>> +++ b/include/dt-bindings/pinctrl/pinctrl-stm32.h
>> @@ -0,0 +1,12 @@
>> +#ifndef _DT_BINDINGS_PINCTRL_STM32_H
>> +#define _DT_BINDINGS_PINCTRL_STM32_H
>> +
>> +#define STM32_PIN_NO(x) ((x) << 8)
>> +#define STM32_GET_PIN_NO(x) ((x) >> 8)
>> +#define STM32_GET_PIN_FUNC(x) ((x) & 0xff)
>> +
>> +#define STM32_PIN_GPIO         0
>> +#define STM32_PIN_AF(x)                ((x) + 1)
>> +#define STM32_PIN_ANALOG       (STM32_PIN_AF(15) + 1)
>> +
>> +#endif /* _DT_BINDINGS_PINCTRL_STM32_H */
>> diff --git a/include/dt-bindings/pinctrl/stm32f429-pinfunc.h
>> b/include/dt-bindings/pinctrl/stm32f429-pinfunc.h
>> new file mode 100644
>> index 0000000..9dd5fd0
>> --- /dev/null
>> +++ b/include/dt-bindings/pinctrl/stm32f429-pinfunc.h
>> @@ -0,0 +1,1241 @@
>> +#ifndef _DT_BINDINGS_STM32F429_PINFUNC_H
>> +#define _DT_BINDINGS_STM32F429_PINFUNC_H
>> +
>> +#include <dt-bindings/pinctrl/pinctrl-stm32.h>
>> +
>> +#define STM32F429_PA0_FUNC_GPIO 0x0
>> +#define STM32F429_PA0_FUNC_TIM2_CH1_TIM2_ETR 0x2
>
>
> Did you expand these out after my feedback (instead of things like:
> STM32_PIN_NO(0) | STM32_PIN_AF(1) )?
Yes.

>
> If so I must have been somewhat unclear.
Most likely I didn't understood what you meant!

>
> I suggesting that, like with the clock driver, there is no need to the
> STM32F429_PAXX_FUNC_YYY macros at all.
>
> Given the way you can enumerate pin config options in stm32f429.dtsi then I
> think stm32f429.dtsi is the only file that will ever include this header? If
> so then why not just plug the values directly into the pinmux fields. Its
> not duplicative and is easier to map back to data sheets.
>
> ~~~
> #define PIN_NO(x) ...
> #define PIN_AF(x) ...
>
> usart1_pins_a: usart1@0 {
>                                 pins1 {
>                                         pinmux = PIN_NO(9) | PIN_AF(7);
>                                         bias-disable;
>                                         drive-push-pull;
>                                         slew-rate = <0>;
>                                 };
>                                 ...
>                         };
> ~~~

The advantage with the defines is that you can see easily which pin we
are talking about.
Moreover, the defines are generated from the datasheet, so it is
painless to generate them.
And it will be consistent with Mediatek implementation, on which I
heavily inspired.

Linus, what is your view?

Thanks,
Maxime
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