Re: [PATCH 3/5] media: ov2640: add primary dt support

[Josh Wu <josh.wu@atmel.com>]

Hi, Laurent

On 12/9/2014 2:39 AM, Laurent Pinchart wrote:
> Hi Josh,
>
> Thank you for the patch.
>
> On Monday 08 December 2014 19:29:05 Josh Wu wrote:
>> Add device tree support for ov2640.
>>
>> Cc: devicetree@vger.kernel.org
>> Signed-off-by: Josh Wu <josh.wu@atmel.com>
>> ---
>> v1 -> v2:
>>    1. use gpiod APIs.
>>    2. change the gpio pin's name according to datasheet.
>>    3. reduce the delay for .reset() function.
>>
>>   drivers/media/i2c/soc_camera/ov2640.c | 86 +++++++++++++++++++++++++++++---
>>   1 file changed, 80 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/media/i2c/soc_camera/ov2640.c
>> b/drivers/media/i2c/soc_camera/ov2640.c index 9ee910d..2a57979 100644
>> --- a/drivers/media/i2c/soc_camera/ov2640.c
>> +++ b/drivers/media/i2c/soc_camera/ov2640.c
>> @@ -18,6 +18,8 @@
>>   #include <linux/i2c.h>
>>   #include <linux/slab.h>
>>   #include <linux/delay.h>
>> +#include <linux/gpio.h>
>> +#include <linux/of_gpio.h>
>>   #include <linux/v4l2-mediabus.h>
>>   #include <linux/videodev2.h>
>>
>> @@ -283,6 +285,10 @@ struct ov2640_priv {
>>   	u32	cfmt_code;
>>   	struct v4l2_clk			*clk;
>>   	const struct ov2640_win_size	*win;
>> +
>> +	struct soc_camera_subdev_desc	ssdd_dt;
>> +	struct gpio_desc *resetb_gpio;
>> +	struct gpio_desc *pwdn_gpio;
>>   };
>>
>>   /*
>> @@ -1047,6 +1053,61 @@ static struct v4l2_subdev_ops ov2640_subdev_ops = {
>>   	.video	= &ov2640_subdev_video_ops,
>>   };
>>
>> +/* OF probe functions */
>> +static int ov2640_hw_power(struct device *dev, int on)
>> +{
>> +	struct i2c_client *client = to_i2c_client(dev);
>> +	struct ov2640_priv *priv = to_ov2640(client);
>> +
>> +	dev_dbg(&client->dev, "%s: %s the camera\n",
>> +			__func__, on ? "ENABLE" : "DISABLE");
>> +
>> +	if (priv->pwdn_gpio && !IS_ERR(priv->pwdn_gpio))
> No need to test for IS_ERR, as the probe function would have failed in that
> case.
right. I'll change it.

>
>> +		gpiod_direction_output(priv->pwdn_gpio, !on);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ov2640_hw_reset(struct device *dev)
>> +{
>> +	struct i2c_client *client = to_i2c_client(dev);
>> +	struct ov2640_priv *priv = to_ov2640(client);
>> +
>> +	/* If enabled, give a reset impulse */
>> +	if (priv->resetb_gpio && !IS_ERR(priv->resetb_gpio)) {
> Same here.
ditto.

>
>> +		gpiod_direction_output(priv->resetb_gpio, 0);
> Given that your DT should specify the active low GPIO flag, and that the gpiod
> API inverts the value in that case, you should set the value to 1 here.

Thanks for the information. I'll fix it.
>
>> +		usleep_range(3000, 5000);
>> +		gpiod_direction_output(priv->resetb_gpio, 1);
> And to 0 here.
yes.

>
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int ov2640_probe_dt(struct i2c_client *client,
>> +		struct ov2640_priv *priv)
>> +{
>> +	priv->resetb_gpio = devm_gpiod_get_optional(&client->dev, "resetb",
>> +			GPIOD_OUT_HIGH);
>> +	if (!priv->resetb_gpio)
>> +		dev_warn(&client->dev, "resetb gpio not found!\n");
> No need to warn here, it's perfectly fine if the reset signal isn't connected
> to a GPIO.
I want to print some information if no GPIO is assigned. So I'd like use 
dev_dbg() here.
What do you feel?

>
>> +	else if (IS_ERR(priv->resetb_gpio))
>> +		return -EINVAL;
>> +
>> +	priv->pwdn_gpio = devm_gpiod_get_optional(&client->dev, "pwdn",
>> +			GPIOD_OUT_HIGH);
>> +	if (!priv->pwdn_gpio)
>> +		dev_warn(&client->dev, "pwdn gpio not found!\n");
> Same here.
ditto.
>
>> +	else if (IS_ERR(priv->pwdn_gpio))
>> +		return -EINVAL;
>> +
>> +	/* Initialize the soc_camera_subdev_desc */
>> +	priv->ssdd_dt.power = ov2640_hw_power;
>> +	priv->ssdd_dt.reset = ov2640_hw_reset;
>> +	client->dev.platform_data = &priv->ssdd_dt;
>> +
>> +	return 0;
>> +}
>> +
>>   /*
>>    * i2c_driver functions
>>    */
>> @@ -1058,12 +1119,6 @@ static int ov2640_probe(struct i2c_client *client,
>>   	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
>>   	int			ret;
>>
>> -	if (!ssdd) {
>> -		dev_err(&adapter->dev,
>> -			"OV2640: Missing platform_data for driver\n");
>> -		return -EINVAL;
>> -	}
>> -
>>   	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
>>   		dev_err(&adapter->dev,
>>   			"OV2640: I2C-Adapter doesn't support SMBUS\n");
>> @@ -1077,6 +1132,18 @@ static int ov2640_probe(struct i2c_client *client,
>>   		return -ENOMEM;
>>   	}
>>
>> +	if (!ssdd) {
>> +		if (client->dev.of_node) {
>> +			ret = ov2640_probe_dt(client, priv);
>> +			if (ret)
>> +				return ret;
>> +		} else {
>> +			dev_err(&client->dev,
>> +				"Missing platform_data for driver\n");
>> +			return  -EINVAL;
>> +		}
> I would test for !client->dev.of_node and return the error, you could then get
> rid of the else and lower the indentation level for the call to
> ov2640_probe_dt().
Okay. I'll change it in next version.

Best Regards,
Josh Wu

>
>> +	}
>> +
>>   	v4l2_i2c_subdev_init(&priv->subdev, client, &ov2640_subdev_ops);
>>   	v4l2_ctrl_handler_init(&priv->hdl, 2);
>>   	v4l2_ctrl_new_std(&priv->hdl, &ov2640_ctrl_ops,
>> @@ -1123,9 +1190,16 @@ static const struct i2c_device_id ov2640_id[] = {
>>   };
>>   MODULE_DEVICE_TABLE(i2c, ov2640_id);
>>
>> +static const struct of_device_id ov2640_of_match[] = {
>> +	{.compatible = "ovti,ov2640", },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, ov2640_of_match);
>> +
>>   static struct i2c_driver ov2640_i2c_driver = {
>>   	.driver = {
>>   		.name = "ov2640",
>> +		.of_match_table = of_match_ptr(ov2640_of_match),
>>   	},
>>   	.probe    = ov2640_probe,
>>   	.remove   = ov2640_remove,