linux-kernel - Re: [PATCH] media: dw9714: add support for powerdown pin

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Message-ID: <aElNcDTLEJTcJs2s@kekkonen.localdomain>
Date: Wed, 11 Jun 2025 09:33:36 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Matthias Fend <matthias.fend@...end.at>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bsp-development.geo@...ca-geosystems.com
Subject: Re: [PATCH] media: dw9714: add support for powerdown pin

Hi Matthias,

Thanks for the patch.

On Wed, Jun 11, 2025 at 09:13:33AM +0200, Matthias Fend wrote:
> Add support for the powerdown pin (xSD), which can be used to put the VCM
> driver into power down mode. This is useful, for example, if the VCM
> driver's power supply cannot be controlled.
> The use of the powerdown pin is optional.

Please rewrap. Most editors can do it for you.

> 
> Signed-off-by: Matthias Fend <matthias.fend@...end.at>
> ---
>  drivers/media/i2c/Kconfig  |  2 +-
>  drivers/media/i2c/dw9714.c | 16 ++++++++++++++++
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index e45ba127069fc0848f1a06ceb789efd3c222c008..e923daeec9c574c5b8c7014b9e83fcbad47866c0 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -748,7 +748,7 @@ config VIDEO_AK7375
>  
>  config VIDEO_DW9714
>  	tristate "DW9714 lens voice coil support"
> -	depends on I2C && VIDEO_DEV
> +	depends on GPIOLIB && I2C && VIDEO_DEV
>  	select MEDIA_CONTROLLER
>  	select VIDEO_V4L2_SUBDEV_API
>  	select V4L2_ASYNC
> diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
> index 2ddd7daa79e28a2cde915b4173fa27e60d5a2b57..5b78c1848f80bc3e32df13d149f3865ff8defe6e 100644
> --- a/drivers/media/i2c/dw9714.c
> +++ b/drivers/media/i2c/dw9714.c
> @@ -2,6 +2,7 @@
>  // Copyright (c) 2015--2017 Intel Corporation.
>  
>  #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> @@ -38,6 +39,7 @@ struct dw9714_device {
>  	struct v4l2_subdev sd;
>  	u16 current_val;
>  	struct regulator *vcc;
> +	struct gpio_desc *powerdown_gpio;
>  };
>  
>  static inline struct dw9714_device *to_dw9714_vcm(struct v4l2_ctrl *ctrl)
> @@ -151,11 +153,20 @@ static int dw9714_probe(struct i2c_client *client)
>  	if (IS_ERR(dw9714_dev->vcc))
>  		return PTR_ERR(dw9714_dev->vcc);
>  
> +	dw9714_dev->powerdown_gpio = devm_gpiod_get_optional(&client->dev,
> +							     "powerdown",
> +							     GPIOD_OUT_LOW);
> +	if (IS_ERR(dw9714_dev->powerdown_gpio))
> +		return dev_err_probe(&client->dev,
> +				     PTR_ERR(dw9714_dev->powerdown_gpio),
> +				     "could not get powerdown gpio\n");
> +
>  	rval = regulator_enable(dw9714_dev->vcc);
>  	if (rval < 0) {
>  		dev_err(&client->dev, "failed to enable vcc: %d\n", rval);
>  		return rval;
>  	}
> +	gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 0);

This seems to be redundant, you're already setting the GPIO low when
acquiring it. Typically the order is different, though: the regulator is
enabled first. Also related to the following comment.

>  
>  	usleep_range(1000, 2000);
>  
> @@ -185,6 +196,7 @@ static int dw9714_probe(struct i2c_client *client)
>  	return 0;
>  
>  err_cleanup:
> +	gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 1);
>  	regulator_disable(dw9714_dev->vcc);

It'd be nice to have a single implementation of the power-on and power-off
sequences. Now there are two.

>  	v4l2_ctrl_handler_free(&dw9714_dev->ctrls_vcm);
>  	media_entity_cleanup(&dw9714_dev->sd.entity);
> @@ -200,6 +212,7 @@ static void dw9714_remove(struct i2c_client *client)
>  
>  	pm_runtime_disable(&client->dev);
>  	if (!pm_runtime_status_suspended(&client->dev)) {
> +		gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 1);
>  		ret = regulator_disable(dw9714_dev->vcc);
>  		if (ret) {
>  			dev_err(&client->dev,
> @@ -234,6 +247,7 @@ static int __maybe_unused dw9714_vcm_suspend(struct device *dev)
>  		usleep_range(DW9714_CTRL_DELAY_US, DW9714_CTRL_DELAY_US + 10);
>  	}
>  
> +	gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 1);
>  	ret = regulator_disable(dw9714_dev->vcc);
>  	if (ret)
>  		dev_err(dev, "Failed to disable vcc: %d\n", ret);
> @@ -262,6 +276,8 @@ static int  __maybe_unused dw9714_vcm_resume(struct device *dev)
>  		dev_err(dev, "Failed to enable vcc: %d\n", ret);
>  		return ret;
>  	}
> +	gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 0);
> +
>  	usleep_range(1000, 2000);
>  
>  	for (val = dw9714_dev->current_val % DW9714_CTRL_STEPS;
> 

-- 
Regards,

Sakari Ailus