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

[Matthias Fend]

Hi Sakari,

thanks for your comments.

Am 11.06.2025 um 11:33 schrieb Sakari Ailus:
> 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.

To me the message body looks line wrapped at 75 columns. The last 
sentence on a new line. At least that is what was intended.
So I think I'm missing something here. Can you please tell me what 
exactly I should change?

> > Signed-off-by: Matthias Fend <matthias.fend@xxxxxxxxx>
> > ---
> >   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.

Yes, that's right. I'll set the pin during initialization so that 
power-down mode is active. So at least the sequence is always the same.

> >   
> >   	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.

Okay, will do so.

Thanks,
 ~Matthias

> >   	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;