Hi Ramiro,

please find some review comments below.

On 02/17/2017 03:14 PM, Ramiro Oliveira wrote:

The OV5647 sensor from Omnivision supports up to 2592x1944 @ 15 fps, RAW 8
and RAW 10 output formats, and MIPI CSI-2 interface.

The driver adds support for 640x480 RAW 8.

Signed-off-by: Ramiro Oliveira <roliveir-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>
---

[snip]

+
+struct ov5647 {
+	struct v4l2_subdev		sd;
+	struct media_pad		pad;
+	struct mutex			lock;
+	struct v4l2_mbus_framefmt	format;
+	unsigned int			width;
+	unsigned int			height;
+	int				power_count;
+	struct clk			*xclk;
+	/* External clock frequency currently supported is 30MHz */
+	u32				xclk_freq;

See a comment about 25MHz vs 30MHz below.

Also I assume you can remove 'xclk_freq' from the struct fields,
it can be replaced by a local variable.

+};

[snip]

+
+static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val)
+{
+	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 < 0) {
+		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",

s/i2c read error/i2c write error/

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

Please remove the empty line above.

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

Assignment of 'i' on declaration is not needed, please remove.

+
+	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;
+
+	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);

Should you add a check of the returned value?

+
+	dev_dbg(&client->dev, "Stream on");

I would suggest to remove dev_dbg(), because ftrace will report to a user,
when this function is called.

Also dev_dbg() in the middle of two I2C transfers in a row looks as being
placed improperly.

+
+	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);

Should you add a check of the returned value?

+
+	dev_dbg(&client->dev, "Stream off");

I would suggest to remove dev_dbg(), because ftrace will report to a user,
when this function is called.

Also dev_dbg() in the middle of two I2C transfers in a row looks as being
placed improperly.

+
+	return ov5647_write(sd, 0x300D, 0x01);
+}
+
+static int set_sw_standby(struct v4l2_subdev *sd, bool standby)
+{
+	int ret;
+	u8 rdval;
+
+	ret = ov5647_read(sd, 0x0100, &rdval);
+	if (ret < 0)
+		return ret;
+
+	if (standby)
+		rdval &= ~0x01;
+	else
+		rdval |= 0x01;
+
+	return ov5647_write(sd, 0x0100, rdval);
+}
+
+static int __sensor_init(struct v4l2_subdev *sd)
+{
+	int ret;
+	u8 resetval;
+	u8 rdval;

It could be possible to put declarations of 'resetval' and 'rdval' on the same line.

+	struct i2c_client *client = v4l2_get_subdevdata(sd);
+
+	dev_dbg(&client->dev, "sensor init\n");
+
+	ret = ov5647_read(sd, 0x0100, &rdval);
+	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);
+}
+
+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);

Now clk_set_rate() is redundant, please remove it.

If once it is needed again, please move it to the .probe function, so
it is called only once in the runtime.

+
+		ret = clk_prepare_enable(ov5647->xclk);

I wonder would it be possible to unload the driver or to unbind the device
and leave the clock unintentionally enabled? If yes, then this is a bug.

+		if (ret < 0) {
+			dev_err(&client->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");

One of two dev_dbg()'s above is apparently redundant.

+		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;
+}
+

[snip]

+
+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;
+
+	sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
+	if (sensor == NULL)

if (!sensor) is a bit shorter.

+		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);
+	}
+
+	sensor->xclk_freq = clk_get_rate(sensor->xclk);
+	if (sensor->xclk_freq != 25000000) {

A comment in "struct ov5647" declaration says about 30MHz, which one is correct?

+		dev_err(dev, "Unsupported clock frequency: %u\n",
+			sensor->xclk_freq);
+		return -EINVAL;
+	}
+
+	mutex_init(&sensor->lock);
+
+	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;
+
+	dev_dbg(&client->dev, "OmniVision OV5647 camera driver probed\n");
+	return 0;
+error:
+	media_entity_cleanup(&sd->entity);
+mutex_remove:
+	mutex_destroy(&sensor->lock);
+	return ret;
+}
+

[snip]

The driver looks good in general IMO.

--
With best wishes,
Vladimir
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html