On 3/9/21 11:20 Péter Ujfalusi wrote:
If this is a 'reset' pin then it's ACTIVE state is when it places the device to _reset_. GPIOD_OUT_LOW == Deasserted state of the GPIO line.
If the reset pin should be pulled low for reset (GPIO_ACTIVE_LOW) and you want the device initially in reset then you need GPIOD_OUT_HIGH, because: GPIOD_OUT_HIGH == Asserted state of the GPIO line.
Same goes for the gpiod_set_value_cansleep(): 0 - deasserted 1 = asserted
and this all depends on how the gpio is defined in DT (GPIO_ACTIVE_LOW/HIGH), which depends on how the documentation refers to the pin...
reset pin: low to keep the device in reset, high to release it from reset: GPIO_ACTIVE_LOW gpiod_set_value_cansleep(0) to enable gpiod_set_value_cansleep(1) to disable
enable pin: high to enable the part, low to disable GPIO_ACTIVE_HIGH gpiod_set_value_cansleep(1) to enable gpiod_set_value_cansleep(0) to disable
In both cases electrical 0: reset/disable electrical 1: enable
I'll change it to be consistent in the next version. Thank you for the explanation.
- if (IS_ERR(reset_gpio)) {
ret = PTR_ERR(reset_gpio);return dev_err_probe(&i2c->dev, ret, "failed to request
GPIO reset
pin"); + }
- if (reset_gpio) {
usleep_range(8000, 10000);gpiod_set_value_cansleep(reset_gpio, 1);usleep_range(1000, 5000);- }
You might want to put the device to reset on remove at minimum.
Okay, thanks.