Re: [PATCH v2 1/2] media: ov9650: support device tree probing

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

On 01/07/2018 05:54 PM, Akinobu Mita wrote:
> The ov9650 driver currently only supports legacy platform data probe.
> This change adds device tree probing.

> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> ---

>  drivers/media/i2c/ov9650.c | 130 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 92 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
> index 69433e1..99a3eab 100644
> --- a/drivers/media/i2c/ov9650.c
> +++ b/drivers/media/i2c/ov9650.c

> -static void __ov965x_set_power(struct ov965x *ov965x, int on)
> +static int __ov965x_set_power(struct ov965x *ov965x, int on)
>  {
>  	if (on) {
> -		ov965x_gpio_set(ov965x->gpios[GPIO_PWDN], 0);
> -		ov965x_gpio_set(ov965x->gpios[GPIO_RST], 0);
> +		int ret = clk_prepare_enable(ov965x->clk);

It seems you rely on the fact clk_prepare_enable() is a nop when passed
argument is NULL, which happens in non-DT case.

> +		if (ret)
> +			return ret;
> +
> +		gpiod_set_value_cansleep(ov965x->gpios[GPIO_PWDN], 0);
> +		gpiod_set_value_cansleep(ov965x->gpios[GPIO_RST], 0);
>  		msleep(25);
>  	} else {
> -		ov965x_gpio_set(ov965x->gpios[GPIO_RST], 1);
> -		ov965x_gpio_set(ov965x->gpios[GPIO_PWDN], 1);
> +		gpiod_set_value_cansleep(ov965x->gpios[GPIO_RST], 1);
> +		gpiod_set_value_cansleep(ov965x->gpios[GPIO_PWDN], 1);
> +
> +		clk_disable_unprepare(ov965x->clk);
>  	}
>  
>  	ov965x->streaming = 0;
> +
> +	return 0;
>  }

> @@ -1408,16 +1414,17 @@ static const struct v4l2_subdev_ops ov965x_subdev_ops = {
>  /*
>   * Reset and power down GPIOs configuration
>   */
> -static int ov965x_configure_gpios(struct ov965x *ov965x,
> -				  const struct ov9650_platform_data *pdata)
> +static int ov965x_configure_gpios_pdata(struct ov965x *ov965x,
> +				const struct ov9650_platform_data *pdata)
>  {
>  	int ret, i;
> +	int gpios[NUM_GPIOS];
>  
> -	ov965x->gpios[GPIO_PWDN] = pdata->gpio_pwdn;
> -	ov965x->gpios[GPIO_RST]  = pdata->gpio_reset;
> +	gpios[GPIO_PWDN] = pdata->gpio_pwdn;
> +	gpios[GPIO_RST]  = pdata->gpio_reset;
>  
>  	for (i = 0; i < ARRAY_SIZE(ov965x->gpios); i++) {
> -		int gpio = ov965x->gpios[i];
> +		int gpio = gpios[i];
>  
>  		if (!gpio_is_valid(gpio))
>  			continue;
> @@ -1427,9 +1434,30 @@ static int ov965x_configure_gpios(struct ov965x *ov965x,
>  			return ret;
>  		v4l2_dbg(1, debug, &ov965x->sd, "set gpio %d to 1\n", gpio);
>  
> -		gpio_set_value(gpio, 1);
> +		gpio_set_value_cansleep(gpio, 1);
>  		gpio_export(gpio, 0);
> -		ov965x->gpios[i] = gpio;
> +		ov965x->gpios[i] = gpio_to_desc(gpio);
> +	}
> +
> +	return 0;
> +}
> +
> +static int ov965x_configure_gpios(struct ov965x *ov965x)
> +{
> +	struct device *dev = &ov965x->client->dev;
> +
> +	ov965x->gpios[GPIO_PWDN] = devm_gpiod_get_optional(dev, "powerdown",
> +							GPIOD_OUT_HIGH);
> +	if (IS_ERR(ov965x->gpios[GPIO_PWDN])) {
> +		dev_info(dev, "can't get %s GPIO\n", "powerdown");
> +		return PTR_ERR(ov965x->gpios[GPIO_PWDN]);
> +	}
> +
> +	ov965x->gpios[GPIO_RST] = devm_gpiod_get_optional(dev, "reset",
> +							GPIOD_OUT_HIGH);
> +	if (IS_ERR(ov965x->gpios[GPIO_RST])) {
> +		dev_info(dev, "can't get %s GPIO\n", "reset");
> +		return PTR_ERR(ov965x->gpios[GPIO_RST]);
>  	}
>  
>  	return 0;
> @@ -1443,7 +1471,10 @@ static int ov965x_detect_sensor(struct v4l2_subdev *sd)
>  	int ret;
>  
>  	mutex_lock(&ov965x->lock);
> -	__ov965x_set_power(ov965x, 1);
> +	ret = __ov965x_set_power(ov965x, 1);
> +	if (ret)
> +		goto out;
> +
>  	msleep(25);
>  
>  	/* Check sensor revision */
> @@ -1463,6 +1494,7 @@ static int ov965x_detect_sensor(struct v4l2_subdev *sd)
>  			ret = -ENODEV;
>  		}
>  	}
> +out:
>  	mutex_unlock(&ov965x->lock);
>  
>  	return ret;
> @@ -1476,23 +1508,39 @@ static int ov965x_probe(struct i2c_client *client,
>  	struct ov965x *ov965x;
>  	int ret;
>  
> -	if (!pdata) {
> -		dev_err(&client->dev, "platform data not specified\n");
> -		return -EINVAL;
> -	}
> -
> -	if (pdata->mclk_frequency == 0) {
> -		dev_err(&client->dev, "MCLK frequency not specified\n");
> -		return -EINVAL;
> -	}
> -
>  	ov965x = devm_kzalloc(&client->dev, sizeof(*ov965x), GFP_KERNEL);
>  	if (!ov965x)
>  		return -ENOMEM;
>  
> -	mutex_init(&ov965x->lock);

I would leave mutex initialization as first thing after the private data
structure allocation, is there a need to move it further?

>  	ov965x->client = client;
> -	ov965x->mclk_frequency = pdata->mclk_frequency;
> +
> +	if (pdata) {
> +		if (pdata->mclk_frequency == 0) {
> +			dev_err(&client->dev, "MCLK frequency not specified\n");
> +			return -EINVAL;
> +		}
> +		ov965x->mclk_frequency = pdata->mclk_frequency;
> +
> +		ret = ov965x_configure_gpios_pdata(ov965x, pdata);
> +		if (ret < 0)
> +			return ret;
> +	} else if (dev_fwnode(&client->dev)) {
> +		ov965x->clk = devm_clk_get(&ov965x->client->dev, NULL);
> +		if (IS_ERR(ov965x->clk))
> +			return PTR_ERR(ov965x->clk);
> +		ov965x->mclk_frequency = clk_get_rate(ov965x->clk);
> +
> +		ret = ov965x_configure_gpios(ov965x);
> +		if (ret < 0)
> +			return ret;
> +	} else {
> +		dev_err(&client->dev,
> +			"Neither platform data nor device property specified\n");
> +
> +		return -EINVAL;
> +	}
> +
> +	mutex_init(&ov965x->lock);
>  
>  	sd = &ov965x->sd;
>  	v4l2_i2c_subdev_init(sd, client, &ov965x_subdev_ops);
> @@ -1502,10 +1550,6 @@ static int ov965x_probe(struct i2c_client *client,
>  	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
>  		     V4L2_SUBDEV_FL_HAS_EVENTS;
>  
> -	ret = ov965x_configure_gpios(ov965x, pdata);
> -	if (ret < 0)
> -		goto err_mutex;
> -
>  	ov965x->pad.flags = MEDIA_PAD_FL_SOURCE;
>  	sd->entity.function = MEDIA_ENT_F_CAM_SENSOR;
>  	ret = media_entity_pads_init(&sd->entity, 1, &ov965x->pad);
> @@ -1561,9 +1605,19 @@ static const struct i2c_device_id ov965x_id[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, ov965x_id);
>  
> +#if IS_ENABLED(CONFIG_OF)

Is there any advantage in using IS_ENABLED() rather than just
#ifdef CONFIG_OF ? of_match_ptr() is defined with just #idef CONFIG_OF/
#else/#endif. I would use simply #ifdef CONFIG_OF here.

Otherwise looks good.

Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

-- 
Regards,
Sylwester