linux-kernel - Re: [PATCH v2 2/6] media: ov5647: Add support for PWDN GPIO.

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Message-ID: <20200618155443.qahjxvlsqckmrgnw@uno.localdomain>
Date:   Thu, 18 Jun 2020 17:54:43 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Roman Kovalivskyi <roman.kovalivskyi@...ballogic.com>
Cc:     linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Luis Oliveira <lolivei@...opsys.com>,
        Niklas Söderlund <niklas.soderlund@...natech.se>,
        Michael Rodin <mrodin@...adit-jv.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Hugues Fruchet <hugues.fruchet@...com>,
        Maxime Ripard <mripard@...nel.org>,
        Adam Ford <aford173@...il.com>,
        Todor Tomov <todor.tomov@...aro.org>,
        Suresh Udipi <sudipi@...adit-jv.com>,
        Andrew Gabbasov <andrew_gabbasov@...tor.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>,
        Dave Stevenson <dave.stevenson@...pberrypi.org>
Subject: Re: [PATCH v2 2/6] media: ov5647: Add support for PWDN GPIO.

Hi Roman,

On Tue, May 19, 2020 at 04:16:17AM +0300, Roman Kovalivskyi wrote:
> From: Dave Stevenson <dave.stevenson@...pberrypi.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@...pberrypi.org>
> Signed-off-by: Roman Kovalivskyi <roman.kovalivskyi@...ballogic.com>
> ---
>  drivers/media/i2c/ov5647.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
>
> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> index 3e587eb0a30e..796cc80f8ee1 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)
> @@ -93,6 +102,11 @@ static inline struct ov5647 *to_state(struct v4l2_subdev *sd)
>  	return container_of(sd, struct ov5647, sd);
>  }
>
> +static inline void msleep_range(unsigned int delay_base)
> +{
> +	usleep_range(delay_base * 1000, delay_base * 1000 + 5000);
> +}
> +

I think I mis-lead you with the comment I gave on v1, as I just notice
the designated timeout is 20 msec, so msleep() is fine. Sorry about
this, I thought we were dealing with a shorter interval.

If that's ok with you I'll send a v3 of this series with Sakari's
comments addressed, rebased on top of the yaml version of the sensor
bindings I sent out a few hours ago.

Thanks
  j

>  static struct regval_list sensor_oe_disable_regs[] = {
>  	{0x3000, 0x00},
>  	{0x3001, 0x00},
> @@ -355,6 +369,11 @@ 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_range(PWDN_ACTIVE_DELAY_MS);
> +		}
> +
>  		ret = clk_prepare_enable(ov5647->xclk);
>  		if (ret < 0) {
>  			dev_err(&client->dev, "clk prepare enable failed\n");
> @@ -392,6 +411,8 @@ 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 +624,10 @@ 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 +641,15 @@ static int ov5647_probe(struct i2c_client *client)
>  	if (ret < 0)
>  		goto mutex_remove;
>
> +	if (sensor->pwdn) {
> +		gpiod_set_value(sensor->pwdn, 0);
> +		msleep_range(PWDN_ACTIVE_DELAY_MS);
> +	}
> +
>  	ret = ov5647_detect(sd);
> +
> +	gpiod_set_value(sensor->pwdn, 1);
> +
>  	if (ret < 0)
>  		goto error;
>
> --
> 2.17.1
>