On 03/09/2021 04:49, Alejandro wrote:
> From: Alejandro Tafalla <atafalla@xxxxxxxxx>
>
> Drive the reset gpio if defined in the DTS node.
>
> Signed-off-by: Alejandro Tafalla <atafalla@xxxxxxxxx>
> ---
> sound/soc/codecs/max98927.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/sound/soc/codecs/max98927.c b/sound/soc/codecs/max98927.c
> index 8b206ee77709..daf06b503433 100644
> --- a/sound/soc/codecs/max98927.c
> +++ b/sound/soc/codecs/max98927.c
> @@ -868,6 +868,7 @@ static int max98927_i2c_probe(struct i2c_client *i2c,
> int ret = 0, value;
> int reg = 0;
> struct max98927_priv *max98927 = NULL;
> + struct gpio_desc *reset_gpio;
>
> max98927 = devm_kzalloc(&i2c->dev,
> sizeof(*max98927), GFP_KERNEL);
> @@ -898,6 +899,19 @@ static int max98927_i2c_probe(struct i2c_client *i2c,
> return ret;
> }
>
> + reset_gpio
> + = devm_gpiod_get_optional(&i2c->dev, "reset", GPIOD_OUT_LOW);
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
> + 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.
> /* Check Revision ID */
> ret = regmap_read(max98927->regmap,
> MAX98927_R01FF_REV_ID, ®);
>
--
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