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SubjectRe: [PATCH 2/4] media: ov5647: Add support for PWDN GPIO.
Hi Roman,
this patch requires the device bindings document to be updated
to report an optional 'powerdown-gpios' property is available and that
it's active HIGH.

On Mon, Apr 13, 2020 at 12:17:45PM +0300, Roman Kovalivskyi 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 nothe 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>
> ---
> 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 3e587eb0a30e..c39e3d20e3ef 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(ov5647->pwdn, 0);
> + msleep(PWDN_ACTIVE_DELAY_MS);

please use usleep_range() according to Documentation/timers/timers-howto.rst

Thanks
j
> + }
> +
> 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(ov5647->pwdn, 1);
> }
>
> /* Update the power count. */
> @@ -603,6 +619,10 @@ 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);
> +
> mutex_init(&sensor->lock);
>
> sd = &sensor->sd;
> @@ -616,7 +636,15 @@ static int ov5647_probe(struct i2c_client *client)
> if (ret < 0)
> goto mutex_remove;
>
> + if (sensor->pwdn) {
> + gpiod_set_value(sensor->pwdn, 0);
> + msleep(PWDN_ACTIVE_DELAY_MS);
> + }
> +
> ret = ov5647_detect(sd);
> +
> + gpiod_set_value(sensor->pwdn, 1);
> +
> if (ret < 0)
> goto error;
>
> --
> 2.17.1
>

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