Re: [PATCH v8 2/2] Add support for OV5647 sensor.

[Vladimir Zapolskiy]

Hello Ramiro,

On 02/13/2017 01:25 PM, Ramiro Oliveira wrote:
> Modes supported:
>  - 640x480 RAW 8
> 

It is a pretty short commit message, please consider to write a couple
of words about the sensor.

> Signed-off-by: Ramiro Oliveira <roliveir@xxxxxxxxxxxx>
> ---

[snip]

> +
> +struct cfg_array {
> +	struct regval_list *regs;
> +	int size;
> +};

struct cfg_array is apparently unused.

> +
> +/**
> + * @short I2C Write operation
> + * @param[in] i2c_client I2C client
> + * @param[in] reg register address
> + * @param[in] val value to write
> + * @return Error code
> + */
> +static int ov5647_write(struct v4l2_subdev *sd, u16 reg, u8 val)
> +{

The comment contents is probably outdated, because it does not describe
the function input arguments properly.

> +	int ret;
> +	unsigned char data[3] = { reg >> 8, reg & 0xff, val};
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ret = i2c_master_send(client, data, 3);
> +	if (ret != 3) {
> +		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
> +				__func__, reg);
> +		return ret < 0 ? ret : -EIO;

Here i2c_master_send() returns only to a negative error or '3', thus
the check is redundant.

Please do 'return ret';

> +	}
> +	return 0;
> +}
> +
> +/**
> + * @short I2C Read operation
> + * @param[in] i2c_client I2C client
> + * @param[in] reg register address
> + * @param[out] val value read
> + * @return Error code
> + */
> +static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val)
> +{

Same as above, the comment must be updated.

> +	int ret;
> +	unsigned char data_w[2] = { reg >> 8, reg & 0xff };
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ret = i2c_master_send(client, data_w, 2);
> +
> +	if (ret < 2) {
> +		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
> +			__func__, reg);
> +		return ret < 0 ? ret : -EIO;


Here i2c_master_send() returns only to a negative error or '2', thus
the check is redundant.

Please do 'return ret';

> +	}
> +
> +	ret = i2c_master_recv(client, val, 1);
> +
> +	if (ret < 1) {
> +		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
> +				__func__, reg);
> +		return ret < 0 ? ret : -EIO;

Here i2c_master_recv() returns only to a negative error or '1', thus
the check is redundant.

Please do 'return ret';

> +	}
> +	return 0;
> +}
> +
> +static int ov5647_write_array(struct v4l2_subdev *sd,
> +				struct regval_list *regs, int array_size)
> +{
> +	int i = 0;
> +	int ret = 0;

Please don't assign a value to 'ret' and please do declarations on a single line.

> +
> +	if (!regs)
> +		return -EINVAL;

!regs is a dead code check, please remove it.

> +
> +	while (i < array_size) {
> +		ret = ov5647_write(sd, regs->addr, regs->data);
> +		if (ret < 0)
> +			return ret;
> +		i++;
> +		regs++;
> +	}

Please do a for-loop, it will save two lines of code:

	for (i = 0; i < array_size; i++) {
		ret = ov5647_write(sd, regs[i].addr, regs[i].data);
		if (ret < 0)
			return ret;
	}

> +	return 0;
> +}
> +
> +static int ov5647_set_virtual_channel(struct v4l2_subdev *sd, int channel)
> +{
> +	u8 channel_id;
> +	int ret = 0;

Please don't assign a value to 'ret' on declaration here.

> +
> +	ret = ov5647_read(sd, 0x4814, &channel_id);
> +	if (ret < 0)
> +		return ret;
> +
> +	channel_id &= ~(3 << 6);
> +	return ov5647_write(sd, 0x4814, channel_id | (channel << 6));
> +}
> +
> +static int ov5647_stream_on(struct v4l2_subdev *sd)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ov5647_write(sd, 0x4202, 0x00);
> +
> +	dev_dbg(&client->dev, "Stream on");
> +
> +	return ov5647_write(sd, 0x300D, 0x00);
> +}
> +
> +static int ov5647_stream_off(struct v4l2_subdev *sd)
> +{
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ov5647_write(sd, 0x4202, 0x0f);
> +
> +	dev_dbg(&client->dev, "Stream off");
> +
> +	return ov5647_write(sd, 0x300D, 0x01);
> +}
> +
> +/**
> + * @short Set SW standby
> + * @param[in] sd v4l2 sd
> + * @param[in] stanby standby mode status (on or off)
> + * @return Error code
> + */
> +static int set_sw_standby(struct v4l2_subdev *sd, bool standby)
> +{
> +	int ret;
> +	unsigned char rdval;

ov5647_read() return value type is 'u8', please change it here and
everywhere else in the code.

> +
> +	ret = ov5647_read(sd, 0x0100, &rdval);
> +	if (ret != 0)

if (ret < 0)

> +		return ret;
> +
> +	if (standby)
> +		rdval &= 0xfe;

Here 'rdval &= ~0x01' would be preferred to emphasize symmetry.

> +	else
> +		rdval |= 0x01;
> +
> +	return ov5647_write(sd, 0x0100, rdval);
> +}
> +
> +/**
> + * @short Initialize sensor
> + * @param[in] sd v4l2 subdev
> + * @param[in] val not used
> + * @return Error code
> + */
> +static int __sensor_init(struct v4l2_subdev *sd)

Same as above, the comment must be updated.

> +{
> +	int ret;
> +	u8 resetval;
> +	u8 rdval;
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	dev_dbg(&client->dev, "sensor init\n");
> +
> +	ret = ov5647_read(sd, 0x0100, &rdval);
> +	if (ret != 0)

if (ret < 0)

> +		return ret;
> +
> +	ret = ov5647_write_array(sd, ov5647_640x480,
> +					ARRAY_SIZE(ov5647_640x480));
> +	if (ret < 0) {
> +		dev_err(&client->dev, "write sensor default regs error\n");
> +		return ret;
> +	}
> +
> +	ret = ov5647_set_virtual_channel(sd, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ov5647_read(sd, 0x0100, &resetval);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!(resetval & 0x01)) {
> +		dev_err(&client->dev, "Device was in SW standby");
> +		ret = ov5647_write(sd, 0x0100, 0x01);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return ov5647_write(sd, 0x4800, 0x04);
> +}
> +
> +/**
> + * @short Control sensor power state
> + * @param[in] sd v4l2 subdev
> + * @param[in] on Sensor power
> + * @return Error code
> + */
> +static int sensor_power(struct v4l2_subdev *sd, int on)
> +{
> +	int ret;
> +	struct ov5647 *ov5647 = to_state(sd);
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ret = 0;
> +	mutex_lock(&ov5647->lock);
> +
> +	if (on && !ov5647->power_count)	{
> +		dev_dbg(&client->dev, "OV5647 power on\n");
> +
> +		clk_set_rate(ov5647->xclk, ov5647->xclk_freq);
> +
> +		ret = clk_prepare_enable(ov5647->xclk);
> +		if (ret < 0) {
> +			dev_err(ov5647->dev, "clk prepare enable failed\n");
> +			goto out;
> +		}
> +
> +		ret = ov5647_write_array(sd, sensor_oe_enable_regs,
> +				ARRAY_SIZE(sensor_oe_enable_regs));
> +		if (ret < 0) {
> +			clk_disable_unprepare(ov5647->xclk);
> +			dev_err(&client->dev,
> +				"write sensor_oe_enable_regs error\n");
> +			goto out;
> +		}
> +
> +		ret = __sensor_init(sd);
> +		if (ret < 0) {
> +			clk_disable_unprepare(ov5647->xclk);
> +			dev_err(&client->dev,
> +				"Camera not available, check Power\n");
> +			goto out;
> +		}
> +	} else if (!on && ov5647->power_count == 1) {
> +		dev_dbg(&client->dev, "OV5647 power off\n");
> +
> +		dev_dbg(&client->dev, "disable oe\n");
> +		ret = ov5647_write_array(sd, sensor_oe_disable_regs,
> +				ARRAY_SIZE(sensor_oe_disable_regs));
> +
> +		if (ret < 0)
> +			dev_dbg(&client->dev, "disable oe failed\n");
> +
> +		ret = set_sw_standby(sd, true);
> +
> +		if (ret < 0)
> +			dev_dbg(&client->dev, "soft stby failed\n");
> +
> +		clk_disable_unprepare(ov5647->xclk);
> +	}
> +
> +	/* Update the power count. */
> +	ov5647->power_count += on ? 1 : -1;
> +	WARN_ON(ov5647->power_count < 0);
> +
> +out:
> +	mutex_unlock(&ov5647->lock);
> +
> +	return ret;
> +}
> +
> +#ifdef CONFIG_VIDEO_ADV_DEBUG
> +/**
> + * @short Get register value
> + * @param[in] sd v4l2 subdev
> + * @param[in] reg register struct
> + * @return Error code
> + */
> +static int sensor_get_register(struct v4l2_subdev *sd,
> +				struct v4l2_dbg_register *reg)
> +{
> +	unsigned char val = 0;

ov5647_read() return value type is 'u8', please change it here and
everywhere else in the code.

Also please don't assign a value to 'val' n declaration.

> +	int ret;
> +
> +	ret = ov5647_read(sd, reg->reg & 0xff, &val);
> +	if (ret != 0)

if (ret < 0)

> +		return ret;
> +
> +	reg->val = val;
> +	reg->size = 1;
> +
> +	return ret;

return 0;

> +}
> +
> +/**
> + * @short Set register value
> + * @param[in] sd v4l2 subdev
> + * @param[in] reg register struct
> + * @return Error code
> + */
> +static int sensor_set_register(struct v4l2_subdev *sd,
> +				const struct v4l2_dbg_register *reg)
> +{
> +	return ov5647_write(sd, reg->reg & 0xff, reg->val & 0xff);
> +}
> +#endif
> +
> +/**
> + * @short Subdev core operations registration
> + */
> +static const struct v4l2_subdev_core_ops subdev_core_ops = {
> +	.s_power		= sensor_power,
> +#ifdef CONFIG_VIDEO_ADV_DEBUG
> +	.g_register		= sensor_get_register,
> +	.s_register		= sensor_set_register,
> +#endif
> +};
> +
> +static int s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	if (!enable)
> +		return ov5647_stream_off(sd);
> +	else
> +		return ov5647_stream_on(sd);

To avoid a negation please do

	if (enable)
		return ov5647_stream_on(sd);
	else
		return ov5647_stream_off(sd);

> +}
> +
> +static const struct v4l2_subdev_video_ops subdev_video_ops = {
> +	.s_stream =		s_stream,
> +};
> +
> +

Please remove one of two empty lines in a row.

> +static int enum_mbus_code(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_pad_config *cfg,
> +				struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	if (code->index > 0)
> +		return -EINVAL;
> +
> +	code->code = MEDIA_BUS_FMT_SBGGR8_1X8;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_pad_ops subdev_pad_ops = {
> +	.enum_mbus_code =	enum_mbus_code,
> +};
> +
> +/**
> + * @short Subdev operations registration
> + *
> + */
> +static const struct v4l2_subdev_ops subdev_ops = {
> +	.core		= &subdev_core_ops,
> +	.video		= &subdev_video_ops,
> +	.pad		= &subdev_pad_ops,
> +};
> +
> +/**
> + * @short Detect camera version and model
> + * @param[in] sd v4l2 subdev
> + * @return Error code
> + */
> +static int ov5647_detect(struct v4l2_subdev *sd)
> +{
> +	unsigned char read;

ov5647_read() return value type is 'u8', please change it here and
everywhere else in the code.

> +	int ret;
> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
> +
> +	ret = ov5647_write(sd, OV5647_SW_RESET, 0x01);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ov5647_read(sd, OV5647_REG_CHIPID_H, &read);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (read != 0x56) {
> +		dev_err(&client->dev, "Wrong model version detected");
> +		return -ENODEV;
> +	}
> +
> +	ret = ov5647_read(sd, OV5647_REG_CHIPID_L, &read);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (read != 0x47) {
> +		dev_err(&client->dev, "Wrong model version detected");
> +		return -ENODEV;
> +	}
> +
> +	return ov5647_write(sd, OV5647_SW_RESET, 0x00);
> +}
> +
> +/**
> + * @short Detect if camera is registered
> + * @param[in] sd v4l2 subdev
> + * @return Error code
> + */
> +static int ov5647_registered(struct v4l2_subdev *sd)
> +{
> +	return 0;
> +}
> +
> +/**
> + * @short Open device
> + * @param[in] sd v4l2 subdev
> + * @param[in] fh v4l2 file handler
> + * @return Error code
> + */
> +static int ov5647_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	struct v4l2_mbus_framefmt *format =
> +				v4l2_subdev_get_try_format(sd, fh->pad, 0);
> +	struct v4l2_rect *crop =
> +				v4l2_subdev_get_try_crop(sd, fh->pad, 0);
> +
> +	crop->left = OV5647_COLUMN_START_DEF;
> +	crop->top = OV5647_ROW_START_DEF;
> +	crop->width = OV5647_WINDOW_WIDTH_DEF;
> +	crop->height = OV5647_WINDOW_HEIGHT_DEF;
> +
> +	format->code = MEDIA_BUS_FMT_SBGGR8_1X8;
> +
> +	format->width = OV5647_WINDOW_WIDTH_DEF;
> +	format->height = OV5647_WINDOW_HEIGHT_DEF;
> +	format->field = V4L2_FIELD_NONE;
> +	format->colorspace = V4L2_COLORSPACE_SRGB;
> +
> +	return sensor_power(sd, true);
> +}
> +
> +/**
> + * @short Open device
> + * @param[in] sd v4l2 subdev
> + * @param[in] fh v4l2 file handler
> + * @return Error code
> + */
> +static int ov5647_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +	return sensor_power(sd, false);
> +}
> +
> +/**
> + * @short Subdev internal operations registration
> + *
> + */
> +static const struct v4l2_subdev_internal_ops ov5647_subdev_internal_ops = {
> +	.registered = ov5647_registered,
> +	.open = ov5647_open,
> +	.close = ov5647_close,
> +};
> +
> +/**
> + * @short Initialization routine - Entry point of the driver
> + * @param[in] client pointer to the i2c client structure
> + * @param[in] id pointer to the i2c device id structure
> + * @return 0 on success and a negative number on failure
> + */
> +static int ov5647_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct ov5647 *sensor;
> +	int ret;
> +	struct v4l2_subdev *sd;
> +
> +	dev_info(&client->dev, "Installing OmniVision OV5647 camera driver\n");

Please remove the informational line, it will pollute the kernel log for no
good reason.

> +
> +	sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
> +	if (sensor == NULL)
> +		return -ENOMEM;
> +
> +	/* get system clock (xclk) */
> +	sensor->xclk = devm_clk_get(dev, "xclk");
> +	if (IS_ERR(sensor->xclk)) {
> +		dev_err(dev, "could not get xclk");
> +		return PTR_ERR(sensor->xclk);
> +	}
> +
> +	ret = of_property_read_u32(dev->of_node, "clock-frequency",
> +				    &sensor->xclk_freq);
> +	if (ret) {
> +		dev_err(dev, "could not get xclk frequency\n");
> +		return ret;
> +	}
> +
> +	mutex_init(&sensor->lock);
> +	sensor->dev = dev;

sensor->dev is unused, please remove it from the 'struct ov5647' declaration.

> +
> +	sd = &sensor->sd;
> +	v4l2_i2c_subdev_init(sd, client, &subdev_ops);
> +	sensor->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
> +	sd->entity.function = MEDIA_ENT_F_CAM_SENSOR;
> +	ret = media_entity_pads_init(&sd->entity, 1, &sensor->pad);
> +	if (ret < 0)
> +		goto mutex_remove;
> +
> +	ret = ov5647_detect(sd);
> +	if (ret < 0)
> +		goto error;
> +
> +	ret = v4l2_async_register_subdev(sd);
> +	if (ret < 0)
> +		goto error;
> +
> +	return 0;
> +error:
> +	media_entity_cleanup(&sd->entity);
> +mutex_remove:
> +	mutex_destroy(&sensor->lock);
> +	return ret;
> +}
> +
> +/**
> + * @short Exit routine - Exit point of the driver
> + * @param[in] client pointer to the i2c client structure
> + * @return 0 on success and a negative number on failure
> + */
> +static int ov5647_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct ov5647 *ov5647 = to_state(sd);
> +
> +	v4l2_async_unregister_subdev(&ov5647->sd);
> +	media_entity_cleanup(&ov5647->sd.entity);
> +	v4l2_device_unregister_subdev(sd);
> +	mutex_destroy(&ov5647->lock);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id ov5647_id[] = {
> +	{ "ov5647", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, ov5647_id);
> +
> +#if IS_ENABLED(CONFIG_OF)

>From Kconfig the driver depends on OF.

> +static const struct of_device_id ov5647_of_match[] = {
> +	{ .compatible = "ovti,ov5647" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, ov5647_of_match);
> +#endif
> +
> +/**
> + * @short i2c driver structure
> + */
> +static struct i2c_driver ov5647_driver = {
> +	.driver = {
> +		.of_match_table = of_match_ptr(ov5647_of_match),

Same comment as above, from Kconfig the driver depends on OF.

> +		.owner	= THIS_MODULE,

.owner is set by the core, please remove it.

> +		.name	= "ov5647",

May be .name = SENSOR_NAME, ?

Otherwise SENSOR_NAME macro is unused and it should be removed.

> +	},
> +	.probe		= ov5647_probe,
> +	.remove		= ov5647_remove,
> +	.id_table	= ov5647_id,
> +};
> +
> +module_i2c_driver(ov5647_driver);
> +
> +MODULE_AUTHOR("Ramiro Oliveira <roliveir@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("A low-level driver for OmniVision ov5647 sensors");
> +MODULE_LICENSE("GPL v2");
> 

--
With best wishes,
Vladimir