According to https://www.kernel.org/doc/Documentation/gpio/consumer.txt,
- all of the gpiod_set_value_xxx() functions operate with the *logical*
value. So in imx290_power_on() the reset signal should be cleared
(de-asserted) with gpiod_set_value_cansleep(imx290->rst_gpio, 0), and in
imx290_power_off() the value of 1 must be used to apply/assert the reset
to the sensor. In the device tree the reset pin is described as
GPIO_ACTIVE_LOW, and gpiod_set_value_xxx() functions take this into
account,
- when devm_gpiod_get_optional() is called with GPIOD_ASIS, the GPIO is
not initialized, and the direction must be set later; using a GPIO
without setting its direction first is illegal and will result in undefined
behavior. Fix this by using GPIOD_OUT_HIGH instead of GPIOD_ASIS (this
asserts the reset signal to the sensor initially).