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From: Lars-Peter Clausen <lars@metafoo.de>
To: "Hannu Hartikainen" <hannu@hrtk.in>,
	"Sa, Nuno" <Nuno.Sa@analog.com>,
	"Antti Keränen" <detegr@rbx.email>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>
Cc: "Hennerich, Michael" <Michael.Hennerich@analog.com>,
	Jonathan Cameron <jic23@kernel.org>
Subject: Re: [RESEND PATCH] iio: adis: set GPIO reset pin direction
Date: Wed, 7 Jul 2021 14:25:06 +0200	[thread overview]
Message-ID: <f82dcd9f-c7f1-1619-9ff2-95066b82c77f@metafoo.de> (raw)
In-Reply-To: <60e595b9.1c69fb81.5284.9247@mx.google.com>

On 7/7/21 1:53 PM, Hannu Hartikainen wrote:
> [...]
> GPIOD_OUT_LOW and GPIOD_OUT_HIGH have different semantics.[1] Is setting
> the pin to use wrong semantics to save one line of code and possibly
> toggle the pin one time less worth it? (The ADIS devices whose
> datasheets I've read have the RST pin as active low, ie. GPIOD_OUT_LOW
> is semantically correct.)

GPIOD_OUT_LOW does not mean that the GPIO is active low. OUT_LOW just 
means that the GPIO is configured as output in the non-asserted 
state[1]. Whether it is active low or active high is configured through 
the flags associated with the GPIO descriptor. E.g. when using 
devicetree this is typically the field after the GPIO offset.

>
> If we really want that, I think the better choice is to use GPIO_ASIS,
> gpiod_direction_output and gpiod_set_raw_value_cansleep and skip
> semantically describing the pin altogether.
Requesting as output is the right solution.


[1] 
https://www.kernel.org/doc/html/latest/driver-api/gpio/consumer.html#obtaining-and-disposing-gpios



  reply	other threads:[~2021-07-07 12:25 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-06  9:29 [RESEND PATCH] iio: adis: set GPIO reset pin direction Antti Keränen
2021-07-07  8:18 ` Lars-Peter Clausen
2021-07-07  8:36 ` Sa, Nuno
2021-07-07 11:53   ` Hannu Hartikainen
2021-07-07 12:25     ` Lars-Peter Clausen [this message]
2021-07-07 13:30       ` Hannu Hartikainen
2021-07-08  9:54         ` [PATCH v2] " Antti Keränen
2021-07-08 10:05           ` Sa, Nuno
2021-07-10 17:35           ` Jonathan Cameron
2021-07-13 17:53           ` Jonathan Cameron
2021-07-14 10:04             ` Antti Keränen
2021-07-14 12:40               ` Jonathan Cameron
2021-07-14 18:25                 ` Antti Keränen
2021-07-17 17:41                   ` Jonathan Cameron
2021-07-07 12:32     ` [RESEND PATCH] " Sa, Nuno
2021-07-07 12:32   ` Lars-Peter Clausen

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