Subject: Re: [V3, 2/2] media: i2c: Add Omnivision OV02A10 camera sensor driver

From: Dongchun Zhu <[email-masked]>
Date: Thu, 5 Sep 2019 23:54:41 +0800

Hi Tomasz,

Thanks very much for your careful review.
Reply to the comments see belows.
Any missing please let me know.

On Wed, 2019-08-21 at 19:30 +0900, Tomasz Figa wrote:
> Hi Dongchun,
> 
> On Mon, Aug 19, 2019 at 11:43:31AM +0800, [email-masked] wrote:
> > From: Dongchun Zhu <[email-masked]>
> > 
> > This patch adds a V4L2 sub-device driver for OV02A10 image sensor.
> > The OV02A10 is a 1/5" CMOS sensor from Omnivision,
> > which supports output format: 10-bit Raw.
> > The OV02A10 has a single MIPI lane interface and use the I2C bus
> > for control and the CSI-2 bus for data.
> > 
> > Signed-off-by: Dongchun Zhu <[email-masked]>
> > ---
> >  MAINTAINERS                 |    1 +
> >  drivers/media/i2c/Kconfig   |   11 +
> >  drivers/media/i2c/Makefile  |    1 +
> >  drivers/media/i2c/ov02a10.c | 1018 +++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 1031 insertions(+)
> >  create mode 100644 drivers/media/i2c/ov02a10.c
> > 
> 
> Thanks for the patch! Please see my comments inline.
> 
> [snip]
> 
> > +#define CHIP_ID                                         0x2509
> > +#define OV02A10_REG_CHIP_ID_H                           0x02
> > +#define OV02A10_REG_CHIP_ID_L                           0x03
> > +#define OV02A10_ID(_msb, _lsb)                          ((_msb) << 8 | (_lsb))
> > +
> > +/* Bit[1] vertical upside down */
> > +/* Bit[0] horizontal mirror */
> > +#define REG_MIRROR_FLIP_CONTROL                         0x3f
> > +
> > +/* Orientation */
> > +#define REG_CONFIG_MIRROR_FLIP		                0x03
> > +
> > +#define REG_PAGE_SWITCH                                 0xfd
> > +#define REG_GLOBAL_EFFECTIVE                            0x01
> > +#define REG_ENABLE                                      BIT(0)
> > +
> > +#define REG_SC_CTRL_MODE                                0xac
> > +#define SC_CTRL_MODE_STANDBY                            0x00
> > +#define SC_CTRL_MODE_STREAMING                          0x01
> > +
> > +#define OV02A10_REG_EXPOSURE_H                          0x03
> > +#define OV02A10_REG_EXPOSURE_L                          0x04
> > +#define	OV02A10_EXPOSURE_MIN                            4
> > +#define	OV02A10_EXPOSURE_STEP                           1
> > +
> > +#define OV02A10_REG_VTS_H                               0x05
> > +#define OV02A10_REG_VTS_L                               0x06
> > +#define OV02A10_VTS_MAX                                 0x209f
> > +#define OV02A10_VTS_MIN                                 0x04cf
> > +#define OV02A10_BASIC_LINE				1224
> > +
> > +#define OV02A10_REG_GAIN                                0x24
> > +#define OV02A10_GAIN_MIN                                0x10
> > +#define OV02A10_GAIN_MAX                                0xf8
> > +#define OV02A10_GAIN_STEP                               0x01
> > +#define OV02A10_GAIN_DEFAULT                            0x40
> > +
> > +#define REG_NULL                                        0xff
> > +
> > +#define OV02A10_LANES                                   1
> > +#define OV02A10_BITS_PER_SAMPLE                         10
> > +
> 
> I think there is something wrong with the indentation in the code above.
> Please use tabs wherever possible.
> 

Sorry for the typo.
Fixed in next release.

> [snip]
> 
> > +
> > +#define to_ov02a10(sd) container_of(sd, struct ov02a10, subdev)
> 
> Please use a static inline function for added compile-time type checks.
> 

Fixed in next release.

> > +
> > +static inline void msleep_range(unsigned int delay_base)
> > +{
> > +	usleep_range(delay_base * 1000, delay_base * 1000 + 500);
> > +}
> 
> Why not just use msleep()?
> 

Generally for shorter sleep(e.g.less than 10ms), usleep_range is
preferred. We would use msleep for bigger sleep.

> > +
> > +/* MIPI color bar enable output */
> > +static const struct regval ov02a10_test_pattern_enable_regs[] = {
> > +	{0xfd, 0x01},
> > +	{0x0d, 0x00},
> > +	{0xb6, 0x01},
> > +	{0x01, 0x01},
> > +	{0xfd, 0x01},
> > +	{0xac, 0x01},
> > +	{REG_NULL, 0x00}
> > +};
> > +
> > +/* MIPI color bar disable output */
> > +static const struct regval ov02a10_test_pattern_disable_regs[] = {
> > +	{0xfd, 0x01},
> > +	{0x0d, 0x00},
> > +	{0xb6, 0x00},
> > +	{0x01, 0x01},
> > +	{0xfd, 0x01},
> > +	{0xac, 0x01},
> > +	{REG_NULL, 0x00}
> > +};
> 
> Hmm, only the register 0xb6 seems to here. Could we just set it directly,
> without these arrays?
> 

R0x0d is another color bar control register.
But R0x01 and R0xac both are essential, which could make color bar
register writing behavior global effective.

> > +
> > +/*
> > + * xvclk 24Mhz
> 
> This seems to assume 24MHz, but the driver allows a range in probe. Is that
> correct?
> 

That's OK.
As the input clock for sensor, the frequency of Master Clock(xvclk) is
regularly 24MHz. But actually the sensor xvclk could allow some little
tolerance. For instance, 1%.

> [snip]]
> 
> > +/* Write a register */
> > +static int ov02a10_write_reg(struct ov02a10 *ov02a10, u8 addr, u8 val)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	u8 buf[2] = {addr, val};
> > +	int ret;
> > +
> > +	ret = i2c_master_send(client, buf, 2);
> > +
> > +	if (ret != 2) {
> > +		dev_err(&client->dev, "%s: error: reg=%x, val=%x\n",
> > +			__func__, addr, val);
> > +		return -EIO;
> > +	}
> > +
> > +	return 0;
> > +}
> 
> Could this be replaced with i2c_smbus_write_byte_data()?
> 

We would have a try using this generic API.

> > +
> > +static int ov02a10_write_array(struct ov02a10 *ov02a10,
> > +			       const struct regval *regs)
> > +{
> > +	u32 i;
> > +	int ret;
> > +
> > +	for (i = 0; regs[i].addr != REG_NULL; i++) {
> > +		ret = ov02a10_write_reg(ov02a10, regs[i].addr, regs[i].val);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +/* Read a register */
> > +static int ov02a10_read_reg(struct ov02a10 *ov02a10, u8 reg, u8 *val)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	u8 data = reg;
> > +	struct i2c_msg msg = {
> > +		.addr	= client->addr,
> > +		.flags	= 0,
> > +		.len	= 1,
> > +		.buf	= &data,
> > +	};
> > +	int ret;
> > +
> > +	ret = i2c_transfer(client->adapter, &msg, 1);
> > +	if (ret < 0)
> > +		goto err_wr;
> > +
> > +	msg.flags = I2C_M_RD;
> > +	ret = i2c_transfer(client->adapter, &msg, 1);
> > +	if (ret < 0)
> > +		goto err_rd;
> 
> Could we just have 2 messages in an array and just call i2c_transfer() once
> for both write and read?
> 
> Or actually it sounds like the i2c_smbus_read_byte_data() helper could work
> here.
> 

Understood. We would have a try, too.

> > +
> > +	*val = data;
> > +	return 0;
> > +
> > +err_rd:
> > +	dev_err(&client->dev, "i2c_transfer --I2C_M_RD failed\n");
> > +err_wr:
> > +	dev_err(&client->dev, "read error: reg=0x%02x: %d\n", reg, ret);
> > +	return ret;
> > +}
> > +
> > +static void ov02a10_fill_fmt(const struct ov02a10_mode *mode,
> > +			     struct v4l2_mbus_framefmt *fmt)
> > +{
> > +	fmt->width = mode->width;
> > +	fmt->height = mode->height;
> > +	fmt->field = V4L2_FIELD_NONE;
> > +}
> > +
> > +static int ov02a10_set_fmt(struct v4l2_subdev *sd,
> > +			   struct v4l2_subdev_pad_config *cfg,
> > +			   struct v4l2_subdev_format *fmt)
> > +{
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +	struct v4l2_mbus_framefmt *mbus_fmt = &fmt->format;
> > +
> > +	mutex_lock(&ov02a10->mutex);
> > +
> > +	if (ov02a10->streaming) {
> > +		mutex_unlock(&ov02a10->mutex);
> > +		return -EBUSY;
> > +	}
> > +
> > +	/* Only one sensor mode supported */
> > +	mbus_fmt->code = ov02a10->fmt.code;
> > +	ov02a10_fill_fmt(ov02a10->cur_mode, mbus_fmt);
> > +	ov02a10->fmt = fmt->format;
> > +
> > +	mutex_unlock(&ov02a10->mutex);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ov02a10_get_fmt(struct v4l2_subdev *sd,
> > +			   struct v4l2_subdev_pad_config *cfg,
> > +			   struct v4l2_subdev_format *fmt)
> > +{
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +	struct v4l2_mbus_framefmt *mbus_fmt = &fmt->format;
> > +
> > +	mutex_lock(&ov02a10->mutex);
> > +
> > +	fmt->format = ov02a10->fmt;
> > +	mbus_fmt->code = ov02a10->fmt.code;
> > +	ov02a10_fill_fmt(ov02a10->cur_mode, mbus_fmt);
> > +
> > +	mutex_unlock(&ov02a10->mutex);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ov02a10_enum_mbus_code(struct v4l2_subdev *sd,
> > +				  struct v4l2_subdev_pad_config *cfg,
> > +				  struct v4l2_subdev_mbus_code_enum *code)
> > +{
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +
> > +	if (code->index >= ARRAY_SIZE(supported_modes) || !(code->index))
> 
> Hmm, ARRAY_SIZE(supported_modes) is 1 and we don't allow code->index to be
> 0 either. Is there a code->index value that wouldn't return an error here?
> 

Fixed in next release.

> > +		return -EINVAL;
> > +
> > +	code->code = ov02a10->fmt.code;
> > +
> > +	return 0;
> > +}
> > +
> > +static int ov02a10_enum_frame_sizes(struct v4l2_subdev *sd,
> > +				    struct v4l2_subdev_pad_config *cfg,
> > +				    struct v4l2_subdev_frame_size_enum *fse)
> > +{
> > +	if (fse->index >= ARRAY_SIZE(supported_modes) || !(fse->index))
> 
> Same here.
> 

Fixed in next release.

> > +		return -EINVAL;
> > +
> > +	fse->min_width  = supported_modes[fse->index].width;
> > +	fse->max_width  = supported_modes[fse->index].width;
> > +	fse->max_height = supported_modes[fse->index].height;
> > +	fse->min_height = supported_modes[fse->index].height;
> > +
> > +	return 0;
> > +}
> > +
> > +static int __ov02a10_power_on(struct ov02a10 *ov02a10)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	struct device *dev = &client->dev;
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(ov02a10->xvclk);
> > +	if (ret < 0) {
> > +		dev_err(dev, "Failed to enable xvclk\n");
> > +		return ret;
> > +	}
> 
> Is it really correct to enable the clock before the regulators?
> 
> According to the datasheet, it should be:
>  - PD pin HIGH,
>  - nRST pin LOW,
>  - DVDDIO and AVDD28 power up and stabilize,
>  - clock enabled,
>  - min 5 ms delay,
>  - PD pin LOW,
>  - min 4 ms delay,
>  - nRST pin HIGH,
>  - min 5 ms delay,
>  - I2C interface ready.
> 

xvclk as the clock source of sensor, we could enable it initially to let
PLL ready. In fact, the power up sequence mainly focus on PD, RST, and
IOVDD/AVDD28/DVDD pins.

> > +
> > +	/* Note: set 0 is high, set 1 is low */
> 
> Why is that? If there is some inverter on the way that should be handled
> outside of this driver. (GPIO DT bindings have flags for this purpose.
> 
> If the pins are nRESET and nPOWERDOWN in the hardware datasheet, we should
> call them like this in the driver too (+/- the lowercase and underscore
> convention).
> 
> According to the datasheet, the reset pin is called RST and inverted, so we should
> call it n_rst, but the powerdown signal, called PD, is not inverted, so pd
> would be the right name.
> 

Sorry. Could make some more explanations about this?

> > +	gpiod_set_value_cansleep(ov02a10->reset_gpio, 1);
> > +	gpiod_set_value_cansleep(ov02a10->powerdown_gpio, 0);
> > +
> > +	ret = regulator_bulk_enable(OV02A10_NUM_SUPPLIES, ov02a10->supplies);
> > +	if (ret < 0) {
> > +		dev_err(dev, "Failed to enable regulators\n");
> > +		goto disable_clk;
> > +	}
> > +	msleep_range(7);
> > +
> > +	gpiod_set_value_cansleep(ov02a10->powerdown_gpio, 1);
> > +	msleep_range(10);
> > +
> > +	gpiod_set_value_cansleep(ov02a10->reset_gpio, 0);
> > +	msleep_range(10);
> > +
> > +	return 0;
> > +
> > +disable_clk:
> > +	clk_disable_unprepare(ov02a10->xvclk);
> > +
> > +	return ret;
> > +}
> > +
> > +static void __ov02a10_power_off(struct ov02a10 *ov02a10)
> > +{
> > +	clk_disable_unprepare(ov02a10->xvclk);
> > +	gpiod_set_value_cansleep(ov02a10->reset_gpio, 1);
> > +	gpiod_set_value_cansleep(ov02a10->powerdown_gpio, 1);
> > +	regulator_bulk_disable(OV02A10_NUM_SUPPLIES, ov02a10->supplies);
> 
> This also doesn't seem to match my datasheet. The sequence there is:
>  - nRST goes LOW,
>  - clock stops,
>  - PD goes HIGH,
>  - regulators are powerd down.
> 

Got it.
This would be fixed in next release.

> > +}
> > +
> > +static int __ov02a10_start_stream(struct ov02a10 *ov02a10)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	int ret;
> > +
> > +	/* Apply default values of current mode */
> > +	ret = ov02a10_write_array(ov02a10, ov02a10->cur_mode->reg_list);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Apply customized values from user */
> > +	ret = __v4l2_ctrl_handler_setup(ov02a10->subdev.ctrl_handler);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Set orientation to 180 degree */
> > +	if (ov02a10->upside_down) {
> > +		ret = ov02a10_write_reg(ov02a10, REG_MIRROR_FLIP_CONTROL,
> > +					REG_CONFIG_MIRROR_FLIP);
> > +		if (ret) {
> > +			dev_err(&client->dev, "%s failed to set orientation\n",
> > +				__func__);
> > +			return ret;
> > +		}
> > +		ret = ov02a10_write_reg(ov02a10, REG_GLOBAL_EFFECTIVE,
> > +					REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	/* Set stream on register */
> > +	return ov02a10_write_reg(ov02a10,
> > +				 REG_SC_CTRL_MODE, SC_CTRL_MODE_STREAMING);
> > +}
> > +
> > +static int __ov02a10_stop_stream(struct ov02a10 *ov02a10)
> > +{
> > +	return ov02a10_write_reg(ov02a10,
> > +				 REG_SC_CTRL_MODE, SC_CTRL_MODE_STANDBY);
> > +}
> > +
> > +static int ov02a10_entity_init_cfg(struct v4l2_subdev *subdev,
> > +				   struct v4l2_subdev_pad_config *cfg)
> > +{
> > +	struct v4l2_subdev_format fmt = { 0 };
> > +
> > +	fmt.which = cfg ? V4L2_SUBDEV_FORMAT_TRY : V4L2_SUBDEV_FORMAT_ACTIVE;
> > +	fmt.format.width = 1600;
> > +	fmt.format.height = 1200;
> 
> Where do these values come from? Should we have some macros for them?
> 

Fixed in next release.

> > +
> > +	ov02a10_set_fmt(subdev, cfg, &fmt);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ov02a10_s_stream(struct v4l2_subdev *sd, int on)
> > +{
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	int ret = 0;
> > +
> > +	mutex_lock(&ov02a10->mutex);
> > +
> > +	if (ov02a10->streaming == on)
> > +		goto unlock_and_return;
> > +
> > +	if (on) {
> > +		ret = pm_runtime_get_sync(&client->dev);
> > +		if (ret < 0) {
> > +			pm_runtime_put_noidle(&client->dev);
> > +			goto unlock_and_return;
> > +		}
> > +
> > +		ret = __ov02a10_start_stream(ov02a10);
> > +		if (ret) {
> > +			__ov02a10_stop_stream(ov02a10);
> > +			ov02a10->streaming = !on;
> > +			goto err_rpm_put;
> > +		}
> > +	} else {
> > +		__ov02a10_stop_stream(ov02a10);
> > +		pm_runtime_put(&client->dev);
> > +	}
> > +
> > +	ov02a10->streaming = on;
> > +	mutex_unlock(&ov02a10->mutex);
> > +
> > +	return ret;
> > +
> > +err_rpm_put:
> > +	pm_runtime_put(&client->dev);
> > +unlock_and_return:
> > +	mutex_unlock(&ov02a10->mutex);
> > +
> > +	return ret;
> > +}
> > +
> > +static int ov02a10_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> > +{
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +	struct v4l2_mbus_framefmt *try_fmt = v4l2_subdev_get_try_format(sd,
> > +									fh->pad,
> > +									0);
> 
> Please separate the initialization from the declaration, because there
> isn't just enough space on this line anymore.
> 

As Sakari pointed out, indeed this function is repeated executed since
init_cfg is implemented already. Thus we would omit the open callback in
next release.

> > +
> > +	mutex_lock(&ov02a10->mutex);
> > +	/* Initialize try_fmt */
> > +	try_fmt->code = ov02a10->fmt.code;
> > +	ov02a10_fill_fmt(&supported_modes[0], try_fmt);
> > +
> > +	mutex_unlock(&ov02a10->mutex);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused ov02a10_runtime_resume(struct device *dev)
> > +{
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +
> > +	return __ov02a10_power_on(ov02a10);
> > +}
> > +
> > +static int __maybe_unused ov02a10_runtime_suspend(struct device *dev)
> > +{
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +
> > +	__ov02a10_power_off(ov02a10);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct dev_pm_ops ov02a10_pm_ops = {
> > +	SET_RUNTIME_PM_OPS(ov02a10_runtime_suspend,
> > +			   ov02a10_runtime_resume, NULL)
> 
> Don't we need to implement and provide system PM ops too?
> 

Fixed in next release.

> > +};
> > +
> > +static int ov02a10_set_test_pattern(struct ov02a10 *ov02a10, s32 value)
> > +{
> > +	if (value)
> > +		return ov02a10_write_array(ov02a10,
> > +					   ov02a10_test_pattern_enable_regs);
> > +
> > +	return ov02a10_write_array(ov02a10,
> > +		ov02a10_test_pattern_disable_regs);
> > +}
> > +
> > +static int ov02a10_set_ctrl(struct v4l2_ctrl *ctrl)
> > +{
> > +	struct ov02a10 *ov02a10 = container_of(ctrl->handler,
> > +					     struct ov02a10, ctrl_handler);
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	s64 max_expo;
> > +	int ret;
> > +
> > +	/* Propagate change of current control to all related controls */
> > +	if (ctrl->id == V4L2_CID_VBLANK) {
> > +		/* Update max exposure while meeting expected vblanking */
> > +		max_expo = ov02a10->cur_mode->height + ctrl->val - 4;
> > +		__v4l2_ctrl_modify_range(ov02a10->exposure,
> > +					 ov02a10->exposure->minimum, max_expo,
> > +					 ov02a10->exposure->step,
> > +					 ov02a10->exposure->default_value);
> > +	}
> > +
> > +	/* V4L2 controls values will be applied only when power is already up */
> > +	if (!pm_runtime_get_if_in_use(&client->dev))
> > +		return 0;
> > +
> > +	switch (ctrl->id) {
> > +	case V4L2_CID_EXPOSURE:
> > +		ret = ov02a10_write_reg(ov02a10, REG_PAGE_SWITCH, REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov02a10_write_reg(ov02a10, OV02A10_REG_EXPOSURE_H,
> > +					((ctrl->val >> 8) & 0xFF));
> > +		if (!ret) {
> > +			ret = ov02a10_write_reg(ov02a10, OV02A10_REG_EXPOSURE_L,
> > +						(ctrl->val & 0xFF));
> > +			if (ret < 0)
> > +				return ret;
> > +		}
> > +		ret = ov02a10_write_reg(ov02a10, REG_GLOBAL_EFFECTIVE,
> > +					REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		break;
> > +	case V4L2_CID_ANALOGUE_GAIN:
> > +		ret = ov02a10_write_reg(ov02a10, REG_PAGE_SWITCH, REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov02a10_write_reg(ov02a10, OV02A10_REG_GAIN,
> > +					(ctrl->val & 0xFF));
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov02a10_write_reg(ov02a10, REG_GLOBAL_EFFECTIVE,
> > +					REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		break;
> > +	case V4L2_CID_VBLANK:
> > +		ret = ov02a10_write_reg(ov02a10, REG_PAGE_SWITCH, REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		ret = ov02a10_write_reg(ov02a10, OV02A10_REG_VTS_H,
> > +					(((ctrl->val +
> > +					ov02a10->cur_mode->height -
> > +					OV02A10_BASIC_LINE) >> 8)
> > +					& 0xFF));
> > +		if (!ret) {
> > +			ret = ov02a10_write_reg(ov02a10, OV02A10_REG_VTS_L,
> > +						((ctrl->val +
> > +						ov02a10->cur_mode->height -
> > +						OV02A10_BASIC_LINE) & 0xFF));
> > +			if (ret < 0)
> > +				return ret;
> > +		}
> > +		ret = ov02a10_write_reg(ov02a10, REG_GLOBAL_EFFECTIVE,
> > +					REG_ENABLE);
> > +		if (ret < 0)
> > +			return ret;
> > +		break;
> > +	case V4L2_CID_TEST_PATTERN:
> > +		ret = ov02a10_set_test_pattern(ov02a10, ctrl->val);
> > +		if (ret < 0)
> > +			return ret;
> > +		break;
> > +	default:
> > +		dev_warn(&client->dev, "%s Unhandled id:0x%x, val:0x%x\n",
> > +			 __func__, ctrl->id, ctrl->val);
> > +		ret = -EINVAL;
> > +		break;
> 
> We shouldn't need to handle this, as the control framework wouldn't call us
> with a control that we didn't register explicitly.
> 

I see other sensors like ov5645 and ov8856 also have this error ctrl id
handle. Did you mean that "default:..." could be omitted?

> > +	};
> > +
> > +	pm_runtime_put(&client->dev);
> > +
> > +	return ret;
> > +}
> > +
> > +static const struct v4l2_subdev_video_ops ov02a10_video_ops = {
> > +	.s_stream = ov02a10_s_stream,
> > +};
> > +
> > +static const struct v4l2_subdev_pad_ops ov02a10_pad_ops = {
> > +	.init_cfg = ov02a10_entity_init_cfg,
> > +	.enum_mbus_code = ov02a10_enum_mbus_code,
> > +	.enum_frame_size = ov02a10_enum_frame_sizes,
> > +	.get_fmt = ov02a10_get_fmt,
> > +	.set_fmt = ov02a10_set_fmt,
> > +};
> > +
> > +static const struct v4l2_subdev_ops ov02a10_subdev_ops = {
> > +	.video	= &ov02a10_video_ops,
> > +	.pad	= &ov02a10_pad_ops,
> > +};
> > +
> > +static const struct media_entity_operations ov02a10_subdev_entity_ops = {
> > +	.link_validate = v4l2_subdev_link_validate,
> > +};
> > +
> > +static const struct v4l2_subdev_internal_ops ov02a10_internal_ops = {
> > +	.open = ov02a10_open,
> > +};
> > +
> > +static const struct v4l2_ctrl_ops ov02a10_ctrl_ops = {
> > +	.s_ctrl = ov02a10_set_ctrl,
> > +};
> > +
> > +static int ov02a10_initialize_controls(struct ov02a10 *ov02a10)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	const struct ov02a10_mode *mode;
> > +	struct v4l2_ctrl_handler *handler;
> > +	struct v4l2_ctrl *ctrl;
> > +	u64 exposure_max;
> > +	u32 pixel_rate, h_blank;
> > +	int ret;
> > +
> > +	handler = &ov02a10->ctrl_handler;
> > +	mode = ov02a10->cur_mode;
> > +	ret = v4l2_ctrl_handler_init(handler, 10);
> 
> I can see 6 controls registered below.
> 

I think handler num could be little more than the implemented num.
But as you suggested, this would be fixed in next release.

> > +	if (ret)
> > +		return ret;
> > +	handler->lock = &ov02a10->mutex;
> > +
> > +	ctrl = v4l2_ctrl_new_int_menu(handler, NULL, V4L2_CID_LINK_FREQ,
> > +				      0, 0, link_freq_menu_items);
> > +	if (ctrl)
> > +		ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > +
> > +	pixel_rate = (link_freq_menu_items[0] * 2 * OV02A10_LANES) /
> > +		     OV02A10_BITS_PER_SAMPLE;
> > +	v4l2_ctrl_new_std(handler, NULL, V4L2_CID_PIXEL_RATE,
> > +			  0, pixel_rate, 1, pixel_rate);
> > +
> > +	h_blank = mode->hts_def - mode->width;
> > +	ov02a10->hblank = v4l2_ctrl_new_std(handler, NULL, V4L2_CID_HBLANK,
> > +					    h_blank, h_blank, 1, h_blank);
> > +	if (ov02a10->hblank)
> > +		ov02a10->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > +
> > +	ov02a10->vblank = v4l2_ctrl_new_std(handler, &ov02a10_ctrl_ops,
> > +					    V4L2_CID_VBLANK, mode->vts_def -
> > +					    mode->height,
> > +					    OV02A10_VTS_MAX - mode->height, 1,
> > +					    mode->vts_def - mode->height);
> > +
> > +	exposure_max = mode->vts_def - 4;
> > +	ov02a10->exposure = v4l2_ctrl_new_std(handler, &ov02a10_ctrl_ops,
> > +					      V4L2_CID_EXPOSURE,
> > +					      OV02A10_EXPOSURE_MIN,
> > +					      exposure_max,
> > +					      OV02A10_EXPOSURE_STEP,
> > +					      mode->exp_def);
> > +
> > +	ov02a10->anal_gain = v4l2_ctrl_new_std(handler, &ov02a10_ctrl_ops,
> > +					       V4L2_CID_ANALOGUE_GAIN,
> > +					       OV02A10_GAIN_MIN,
> > +					       OV02A10_GAIN_MAX,
> > +					       OV02A10_GAIN_STEP,
> > +					       OV02A10_GAIN_DEFAULT);
> > +
> > +	ov02a10->test_pattern =
> > +	   v4l2_ctrl_new_std_menu_items(handler,
> > +					&ov02a10_ctrl_ops,
> > +					V4L2_CID_TEST_PATTERN,
> > +					ARRAY_SIZE(ov02a10_test_pattern_menu) -
> > +					1, 0, 0, ov02a10_test_pattern_menu);
> > +
> > +	if (handler->error) {
> > +		ret = handler->error;
> > +		dev_err(&client->dev,
> > +			"Failed to init controls(%d)\n", ret);
> > +		goto err_free_handler;
> > +	}
> > +
> > +	ov02a10->subdev.ctrl_handler = handler;
> > +
> > +	return 0;
> > +
> > +err_free_handler:
> > +	v4l2_ctrl_handler_free(handler);
> > +
> > +	return ret;
> > +}
> > +
> > +static int ov02a10_check_sensor_id(struct ov02a10 *ov02a10)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	u16 id;
> > +	u8 pid = 0;
> > +	u8 ver = 0;
> > +	int ret;
> > +
> > +	/* Check sensor revision */
> > +	ret = ov02a10_read_reg(ov02a10, OV02A10_REG_CHIP_ID_H, &pid);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = ov02a10_read_reg(ov02a10, OV02A10_REG_CHIP_ID_L, &ver);
> > +	if (ret)
> > +		return ret;
> > +
> > +	id = OV02A10_ID(pid, ver);
> > +	if (id != CHIP_ID) {
> > +		dev_err(&client->dev, "Unexpected sensor id(%04x)\n", id);
> > +		return ret;
> > +	}
> > +
> > +	dev_info(&client->dev, "Detected OV%04X sensor\n", id);
> > +
> > +	return 0;
> > +}
> > +
> > +static int ov02a10_configure_regulators(struct ov02a10 *ov02a10)
> > +{
> > +	struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < OV02A10_NUM_SUPPLIES; i++)
> > +		ov02a10->supplies[i].supply = ov02a10_supply_names[i];
> > +
> > +	return devm_regulator_bulk_get(&client->dev,
> > +				       OV02A10_NUM_SUPPLIES,
> > +				       ov02a10->supplies);
> > +}
> 
> I think we can just have this directly inside probe.
> 

Understood.
We would have a try.

> > +
> > +static int ov02a10_probe(struct i2c_client *client)
> > +{
> > +	struct device *dev = &client->dev;
> > +	struct ov02a10 *ov02a10;
> > +	u32 rotation;
> > +	u32 xclk_freq;
> > +	int ret;
> > +
> > +	ov02a10 = devm_kzalloc(dev, sizeof(*ov02a10), GFP_KERNEL);
> > +	if (!ov02a10)
> > +		return -ENOMEM;
> > +
> > +	v4l2_i2c_subdev_init(&ov02a10->subdev, client, &ov02a10_subdev_ops);
> > +	ov02a10->fmt.code = MEDIA_BUS_FMT_SBGGR10_1X10;
> > +
> > +	/* Optional indication of physical rotation of sensor */
> > +	ret = fwnode_property_read_u32(dev_fwnode(dev), "rotation",
> > +				       &rotation);
> > +	if (!ret) {
> > +		switch (rotation) {
> > +		case 180:
> > +			ov02a10->upside_down = true;
> > +			ov02a10->fmt.code = MEDIA_BUS_FMT_SRGGB10_1X10;
> > +			break;
> > +		case 0:
> > +			break;
> > +		default:
> > +			dev_warn(dev, "%u degrees rotation is not supported, ignoring...\n",
> > +				 rotation);
> > +		}
> > +	}
> > +
> > +	/* Get system clock (xvclk) */
> > +	ov02a10->xvclk = devm_clk_get(dev, "xvclk");
> > +	if (IS_ERR(ov02a10->xvclk)) {
> > +		dev_err(dev, "Failed to get xvclk\n");
> > +		return -EINVAL;
> > +	}
> 
> Hmm, it's called eclk in my datasheet.
> 

Does this really matter?
Should we follow the common naming, refer to other sensors?

> > +
> > +	ret = of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to get xclk frequency\n");
> > +		return ret;
> > +	}
> > +
> > +	/* External clock must be 24MHz, allow 1% tolerance */
> > +	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> 
> How do we support a range of frequencies? I don't see the driver calculate
> any register values based on this frequency. Are you sure that the register
> arrays don't assume one specific frequency?
> 

In fact, clock-frequency defined in DT is always 24MHz, which is the
clock frequency that sensor requires to keep itself work normally.

> > +		dev_err(dev, "external clock frequency %u is not supported\n",
> > +			xclk_freq);
> > +		return -EINVAL;
> > +	}
> > +	dev_dbg(dev, "external clock frequency %u\n", xclk_freq);
> > +
> > +	ret = clk_set_rate(ov02a10->xvclk, xclk_freq);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to set xvclk frequency (24MHz)\n");
> > +		return ret;
> > +	}
> > +
> > +	ov02a10->powerdown_gpio = devm_gpiod_get(dev, "powerdown",
> > +						 GPIOD_OUT_LOW);
> 
> Hmm, shouldn't this be HIGH? At least the datasheet has it so for the
> powered down state.
> 

The gpio state for this API callback seems to be inverse.

> > +	if (IS_ERR(ov02a10->powerdown_gpio)) {
> > +		dev_err(dev, "Failed to get powerdown-gpios\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	ov02a10->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> 
> Also LOW here, similarly to the above.
> 

Ditto.

> > +	if (IS_ERR(ov02a10->reset_gpio)) {
> > +		dev_err(dev, "Failed to get reset-gpios\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = ov02a10_configure_regulators(ov02a10);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to get power regulators\n");
> > +		return ret;
> > +	}
> > +
> > +	mutex_init(&ov02a10->mutex);
> > +	ov02a10->cur_mode = &supported_modes[0];
> > +	ret = ov02a10_initialize_controls(ov02a10);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to initialize controls\n");
> > +		goto err_destroy_mutex;
> > +	}
> > +
> > +	ret = __ov02a10_power_on(ov02a10);
> > +	if (ret)
> > +		goto err_free_handler;
> > +
> > +	ret = ov02a10_check_sensor_id(ov02a10);
> > +	if (ret)
> > +		goto err_power_off;
> > +
> > +	ov02a10->subdev.internal_ops = &ov02a10_internal_ops;
> > +	ov02a10->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > +	ov02a10->subdev.entity.ops = &ov02a10_subdev_entity_ops;
> > +	ov02a10->subdev.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> > +	ov02a10->pad.flags = MEDIA_PAD_FL_SOURCE;
> > +	ret = media_entity_pads_init(&ov02a10->subdev.entity, 1, &ov02a10->pad);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to init entity pads: %d", ret);
> > +		goto err_power_off;
> > +	}
> > +
> > +	ret = v4l2_async_register_subdev(&ov02a10->subdev);
> > +	if (ret) {
> > +		dev_err(dev, "failed to register V4L2 subdev: %d",
> > +			ret);
> > +		goto err_clean_entity;
> > +	}
> > +
> > +	pm_runtime_set_active(dev);
> > +	pm_runtime_enable(dev);
> > +	pm_runtime_idle(dev);
> > +
> > +	dev_info(dev, "ov02a10 probe --\n");
> 
> Please remove this.
> 

Fixed in next release.

> > +	return 0;
> > +
> > +err_clean_entity:
> > +	media_entity_cleanup(&ov02a10->subdev.entity);
> > +err_power_off:
> > +	__ov02a10_power_off(ov02a10);
> > +err_free_handler:
> > +	v4l2_ctrl_handler_free(ov02a10->subdev.ctrl_handler);
> > +err_destroy_mutex:
> > +	mutex_destroy(&ov02a10->mutex);
> > +
> > +	return ret;
> > +}
> > +
> > +static int ov02a10_remove(struct i2c_client *client)
> > +{
> > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > +	struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +
> > +	v4l2_async_unregister_subdev(sd);
> > +	media_entity_cleanup(&sd->entity);
> > +	v4l2_ctrl_handler_free(sd->ctrl_handler);
> > +	pm_runtime_disable(&client->dev);
> > +	if (!pm_runtime_status_suspended(&client->dev))
> > +		__ov02a10_power_off(ov02a10);
> > +	pm_runtime_set_suspended(&client->dev);
> > +	mutex_destroy(&ov02a10->mutex);
> > +
> > +	return 0;
> > +}
> > +
> > +#if IS_ENABLED(CONFIG_OF)
> > +static const struct of_device_id ov02a10_of_match[] = {
> > +	{ .compatible = "ovti,ov02a10" },
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(of, ov02a10_of_match);
> > +#endif
> > +
> > +static struct i2c_driver ov02a10_i2c_driver = {
> > +	.driver = {
> > +		.name = "ov02a10",
> > +		.pm = &ov02a10_pm_ops,
> > +		.of_match_table = ov02a10_of_match,
> 
> Please use of_match_ptr() wrapper.
> 

Sorry. I am a little confused now.
It seems that Sakari had one different ideas about this.
https://patchwork.kernel.org/patch/10957225/

> Best regards,
> Tomasz

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