linux-kernel - RE: [V3 1/2] ASoC: max98390: Add reset gpio control

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Date:   Mon, 28 Mar 2022 07:42:42 +0000
From:   "Sa, Nuno" <Nuno.Sa@...log.com>
To:     Steve Lee <steve.lee.analog@...il.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "ryans.lee@...imintegrated.com" <ryans.lee@...imintegrated.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>
CC:     "krzk@...nel.org" <krzk@...nel.org>
Subject: RE: [V3 1/2] ASoC: max98390: Add reset gpio control

> From: Steve Lee <steve.lee.analog@...il.com>
> Sent: Monday, March 28, 2022 4:12 AM
> To: lgirdwood@...il.com; broonie@...nel.org; perex@...ex.cz;
> tiwai@...e.com; ryans.lee@...imintegrated.com; linux-
> kernel@...r.kernel.org; alsa-devel@...a-project.org
> Cc: krzk@...nel.org; Sa, Nuno <Nuno.Sa@...log.com>; Steve Lee
> <steve.lee.analog@...il.com>
> Subject: [V3 1/2] ASoC: max98390: Add reset gpio control
> 
> [External]
> 
>  Add reset gpio control to support RESET PIN connected to gpio.
> 
> Signed-off-by: Steve Lee <steve.lee.analog@...il.com>
> ---
>  sound/soc/codecs/max98390.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/sound/soc/codecs/max98390.c
> b/sound/soc/codecs/max98390.c
> index 40fd6f363f35..05df9b85d9b0 100644
> --- a/sound/soc/codecs/max98390.c
> +++ b/sound/soc/codecs/max98390.c
> @@ -1022,6 +1022,7 @@ static int max98390_i2c_probe(struct
> i2c_client *i2c,
> 
>  	struct max98390_priv *max98390 = NULL;
>  	struct i2c_adapter *adapter = i2c->adapter;
> +	struct gpio_desc *reset_gpio;
> 
>  	ret = i2c_check_functionality(adapter,
>  		I2C_FUNC_SMBUS_BYTE
> @@ -1073,6 +1074,17 @@ static int max98390_i2c_probe(struct
> i2c_client *i2c,
>  		return ret;
>  	}
> 
> +	reset_gpio = devm_gpiod_get_optional(&i2c->dev,
> +					     "reset", GPIOD_OUT_LOW);
> +
> +	/* Power on device */
> +	if (reset_gpio) {
> +		usleep_range(1000, 2000);
> +		/* bring out of reset */
> +		gpiod_set_value_cansleep(reset_gpio, 1);

Note this will set the gpio in the asserted state. Being it active low, this will
do the opposite thing that you are trying to accomplish...

- Nuno Sá