On 7/7/21 10:36 AM, Sa, Nuno wrote:
From: Antti Keränen <detegr@rbx.email>
Sent: Tuesday, July 6, 2021 11:29 AM
To: linux-iio@xxxxxxxxxxxxxxx
Cc: Antti Keränen <detegr@rbx.email>; Hannu Hartikainen
<hannu@xxxxxxx>; Lars-Peter Clausen <lars@xxxxxxxxxx>; Hennerich,
Michael <Michael.Hennerich@xxxxxxxxxx>; Sa, Nuno
<Nuno.Sa@xxxxxxxxxx>; Jonathan Cameron <jic23@xxxxxxxxxx>
Subject: [RESEND PATCH] iio: adis: set GPIO reset pin direction
Use GPIOD_OUT_LOW instead of GPIOD_ASIS as the reset pin needs
to be an
active low output pin.
Suggested-by: Hannu Hartikainen <hannu@xxxxxxx>
Signed-off-by: Antti Keränen <detegr@rbx.email>
---
The documentation of GPIO consumer interface states:
Be aware that there is no default direction for GPIOs. Therefore,
**using a GPIO without setting its direction first is illegal and will
result in undefined behavior!**
Therefore the direction of the reset GPIO pin should be set as output.
drivers/iio/imu/adis.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/imu/adis.c b/drivers/iio/imu/adis.c
index 319b64b2fd88..7f13b3763732 100644
--- a/drivers/iio/imu/adis.c
+++ b/drivers/iio/imu/adis.c
@@ -415,7 +415,7 @@ int __adis_initial_startup(struct adis *adis)
int ret;
/* check if the device has rst pin low */
- gpio = devm_gpiod_get_optional(&adis->spi->dev, "reset",
GPIOD_ASIS);
+ gpio = devm_gpiod_get_optional(&adis->spi->dev, "reset",
GPIOD_OUT_LOW);
if (IS_ERR(gpio))
return PTR_ERR(gpio);
Hi,
Thanks for the patch. Forcing the device reset was intentional
(thus the GPIO_ASIS). But what Lars is suggesting is a good idea
and a neat improvement here.
GPIO_ASIS leaves the direction of the GPIO untouched. If the default is
input, the GPIO will stay as an input, in which case triggering the
reset does not work.
