Re: [libcamera-devel] [PATCH 03/25] media: ov5647: Add support for PWDN GPIO.

[Dafna Hirschfeld <dafna.hirschfeld@collabora.com>]

On 23.06.20 12:07, Jacopo Mondi wrote:
> From: Dave Stevenson <dave.stevenson@raspberrypi.org>
> 
> Add support for an optional GPIO connected to PWDN on the sensor. This
> allows the use of hardware standby mode where internal device clock
> and circuit activities are halted.
> 
> Please note that power is off when PWDN is high.
> 
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
> Signed-off-by: Roman Kovalivskyi <roman.kovalivskyi@globallogic.com>
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>   drivers/media/i2c/ov5647.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> index e7d2e5b4ad4b9..105ff7f899b34 100644
> --- a/drivers/media/i2c/ov5647.c
> +++ b/drivers/media/i2c/ov5647.c
> @@ -21,6 +21,7 @@
>   
>   #include <linux/clk.h>
>   #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>   #include <linux/i2c.h>
>   #include <linux/init.h>
>   #include <linux/io.h>
> @@ -35,6 +36,13 @@
>   
>   #define SENSOR_NAME "ov5647"
>   
> +/*
> + * From the datasheet, "20ms after PWDN goes low or 20ms after RESETB goes
> + * high if reset is inserted after PWDN goes high, host can access sensor's
> + * SCCB to initialize sensor."
> + */
> +#define PWDN_ACTIVE_DELAY_MS	20
> +
>   #define MIPI_CTRL00_CLOCK_LANE_GATE		BIT(5)
>   #define MIPI_CTRL00_BUS_IDLE			BIT(2)
>   #define MIPI_CTRL00_CLOCK_LANE_DISABLE		BIT(0)
> @@ -86,6 +94,7 @@ struct ov5647 {
>   	unsigned int			height;
>   	int				power_count;
>   	struct clk			*xclk;
> +	struct gpio_desc		*pwdn;
>   };
>   
>   static inline struct ov5647 *to_state(struct v4l2_subdev *sd)
> @@ -355,6 +364,11 @@ static int ov5647_sensor_power(struct v4l2_subdev *sd, int on)
>   	if (on && !ov5647->power_count)	{
>   		dev_dbg(&client->dev, "OV5647 power on\n");
>   
> +		if (ov5647->pwdn) {
> +			gpiod_set_value_cansleep(ov5647->pwdn, 0);
> +			msleep(PWDN_ACTIVE_DELAY_MS);
> +		}
> +
>   		ret = clk_prepare_enable(ov5647->xclk);
>   		if (ret < 0) {
>   			dev_err(&client->dev, "clk prepare enable failed\n");
> @@ -392,6 +406,8 @@ static int ov5647_sensor_power(struct v4l2_subdev *sd, int on)
>   			dev_dbg(&client->dev, "soft stby failed\n");
>   
>   		clk_disable_unprepare(ov5647->xclk);
> +
> +		gpiod_set_value_cansleep(ov5647->pwdn, 1);
>   	}
>   
>   	/* Update the power count. */
> @@ -581,6 +597,10 @@ static int ov5647_probe(struct i2c_client *client)
>   		return -EINVAL;
>   	}
>   
> +	/* Request the power down GPIO asserted */
> +	sensor->pwdn = devm_gpiod_get_optional(&client->dev, "pwdn",
> +					       GPIOD_OUT_HIGH);

Hi,
I see that other drivers check for error from 'devm_gpiod_get_optional'
using 'IS_ERR'

Thanks,
Dafna

> +
>   	mutex_init(&sensor->lock);
>   
>   	sd = &sensor->sd;
> @@ -594,7 +614,15 @@ static int ov5647_probe(struct i2c_client *client)
>   	if (ret < 0)
>   		goto mutex_remove;
>   
> +	if (sensor->pwdn) {
> +		gpiod_set_value_cansleep(sensor->pwdn, 0);
> +		msleep(PWDN_ACTIVE_DELAY_MS);
> +	}
> +
>   	ret = ov5647_detect(sd);
> +
> +	gpiod_set_value_cansleep(sensor->pwdn, 1);
> +
>   	if (ret < 0)
>   		goto error;
>   
>