linux-kernel - Re: [PATCH] ARM: at91: at91sam9x5: sets NPCS0 (PA14) back to GPIO

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Message-ID: <53D21C57.3010805@aksignal.cz>
Date:	Fri, 25 Jul 2014 10:59:03 +0200
From:	Jiří Prchal <jiri.prchal@...ignal.cz>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	devicetree@...r.kernel.org, nicolas.ferre@...el.com,
	linux-arm-kernel@...ts.infradead.org,
	Bo Shen <voice.shen@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: at91: at91sam9x5: sets NPCS0 (PA14) back to GPIO



Dne 25.7.2014 v 10:54 Alexandre Belloni napsal(a):
> On 25/07/2014 at 10:37:31 +0200, Jiří Prchal wrote :
>>
>>
>> Dne 25.7.2014 v 10:30 Alexandre Belloni napsal(a):
>>> Hi,
>>>
>>> On 25/07/2014 at 08:14:40 +0200, Jiří Prchal wrote :
>>>> I'm using custom board. My spi node:
>>>> 			spi0: spi@...00000 {
>>>
>>> You should override the pinctrl here as you are using gpios for the cs.
>>> 				pinctrl-0 = <&pinctrl_spi0_custom>;
>>>
>>>> 				status = "okay";
>>>> 				cs-gpios = <&pioA 23 0
>>>> 					    &pioA 22 0
>>>> 					    &pioC 29 0
>>>> 					    &pioA 14 0>;
>>>>
>>>
>>> 		pinctrl@...ff400 {
>>> 				spi0 {
>>> 					 pinctrl_spi0_custom: spi0-custom {
>>> 							 atmel,pins =
>>> 									 <AT91_PIOA 23 AT91_PERIPH_GPIO AT91_PINCTRL_NONE>,
>>> 									 <AT91_PIOA 22 AT91_PERIPH_GPIO AT91_PINCTRL_NONE>,
>>> 									 <AT91_PIOC 29 AT91_PERIPH_GPIO AT91_PINCTRL_NONE>,
>>> 									 <AT91_PIOA 14 AT91_PERIPH_GPIO AT91_PINCTRL_NONE>;
>>> 					 };
>>> 				};
>>> 		};
>>>
>> Of course, it's the way, but in all other drivers, for example LEDS,
>> it's not needed. And in other way, if I will not use PA14 at all,
>> the pin will goes down every spi transfer.
>
> You must not assumed that the pins are muxed to their default state
> which is gpio and you should set the pinctrl accordingly for each
> device.
>
> If you don't use PA14 at all, then you don't really care about its
> state...
Yes and no, what about on board is populated some chip on PA14, but for some reason at this time I don't need it and not 
defined in DT?
>
>
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