Re: [PATCH 5/6] media: i2c: ov9282: Add regulator support

["Alessandrelli, Daniele" <daniele.alessandrelli@intel.com>]

On Mon, 2022-07-11 at 10:16 +0200, Alexander Stein wrote:
> Need in case the sensors is supplied by a switchable regulator.
> 
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> ---
>  drivers/media/i2c/ov9282.c | 41 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> index 04fda8222e07..c3faf11a99b5 100644
> --- a/drivers/media/i2c/ov9282.c
> +++ b/drivers/media/i2c/ov9282.c
> @@ -11,6 +11,7 @@
>  #include <linux/i2c.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
>  
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-fwnode.h>
> @@ -55,6 +56,14 @@
>  #define OV9282_REG_MIN         0x00
>  #define OV9282_REG_MAX         0xfffff
>  
> +static const char * const ov9282_supply_names[] = {
> +       "avdd",         /* Analog power */
> +       "dovdd",        /* Digital I/O power */
> +       "dvdd",         /* Digital core power */
> +};
> +
> +#define OV9282_NUM_SUPPLIES ARRAY_SIZE(ov9282_supply_names)
> +
>  /**
>   * struct ov9282_reg - ov9282 sensor register
>   * @address: Register address
> @@ -127,6 +136,7 @@ struct ov9282 {
>         struct media_pad pad;
>         struct gpio_desc *reset_gpio;
>         struct clk *inclk;
> +       struct regulator_bulk_data supplies[OV9282_NUM_SUPPLIES];
>         struct v4l2_ctrl_handler ctrl_handler;
>         struct v4l2_ctrl *link_freq_ctrl;
>         struct v4l2_ctrl *pclk_ctrl;
> @@ -883,10 +893,18 @@ static int ov9282_power_on(struct device *dev)
>                 goto error_reset;
>         }
>  
> +       ret = regulator_bulk_enable(ARRAY_SIZE(ov9282->supplies), ov9282->supplies);
> +       if (ret) {
> +               dev_err(dev, "Failed to enable regulators\n");
> +               goto disable_clk;
> +       }
> +
>         usleep_range(400, 600);
>  
>         return 0;
>  
> +disable_clk:
> +       clk_disable_unprepare(ov9282->inclk);
>  error_reset:
>         gpiod_set_value_cansleep(ov9282->reset_gpio, 0);
>  
> @@ -903,6 +921,11 @@ static int ov9282_power_off(struct device *dev)
>  {
>         struct v4l2_subdev *sd = dev_get_drvdata(dev);
>         struct ov9282 *ov9282 = to_ov9282(sd);
> +       int ret;
> +
> +       ret = regulator_bulk_disable(ARRAY_SIZE(ov9282->supplies), ov9282->supplies);
> +       if (ret)
> +               dev_err(ov9282->dev, "Failed to disable supplies: %d\n", ret);

I'm not sure that checking the return value is needed.
'regulator_bulk_disable()' already prints an error message in case of
failure.

The majority of the drivers in "drivers/media/i2c" don't seem to check
it.

>  
>         gpiod_set_value_cansleep(ov9282->reset_gpio, 0);
>  
> @@ -996,6 +1019,18 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>         return 0;
>  }
>  
> +static int ov9282_configure_regulators(struct ov9282 *ov9282)

I would call this function something like 'ov9282_get_regulators()'.

> +{
> +       unsigned int i;
> +
> +       for (i = 0; i < ARRAY_SIZE(ov9282->supplies); i++)
> +               ov9282->supplies[i].supply = ov9282_supply_names[i];
> +
> +       return devm_regulator_bulk_get(ov9282->dev,
> +                                      ARRAY_SIZE(ov9282->supplies),
> +                                      ov9282->supplies);
> +}
> +
>  /**
>   * ov9282_probe() - I2C client device binding
>   * @client: pointer to i2c client device
> @@ -1022,6 +1057,12 @@ static int ov9282_probe(struct i2c_client *client)
>                 return ret;
>         }
>  
> +       ret = ov9282_configure_regulators(ov9282);
> +       if (ret) {
> +               dev_err(&client->dev, "Failed to get power regulators\n");
> +               return ret;
> +       }
> +
>         mutex_init(&ov9282->mutex);
>  
>         ret = ov9282_power_on(ov9282->dev);