drivers: video: ov7725: add sensor driver for ov7725

[lgl88911]

This patch adds the driver for Omnivision OV7725
Color CMOS VGA Sensor.

The driver currently provides a simple capture
function, the output format only provides
RGB565,640x480.

Signed-off-by: Frank Li lgl88911@163.com

[loicpoulain]

@lgl88911, It looks interesting, but could you please split it in several commits, at least one for the dts changes, one for the new ov driver and one for the sample.

[lgl88911]

@lgl88911, It looks interesting, but could you please split it in several commits, at least one for the dts changes, one for the new ov driver and one for the sample.
Thanks for review, the PR will be close and I divided this commit into three:

1. OV7725 driver drivers: video: ov7725: add sensor driver for ov7725 #30787
   In order to avoid CI fail, After drivers: video: ov7725: add sensor driver for ov7725 #30787 be merged, the following two branches will make a pull request.
2. mm_swiftio support OV7725, https://github.com/lgl88911/zephyr/tree/mm_swiftio_ov7725
3. sample，https://github.com/lgl88911/zephyr/tree/add_ov7725_sample

[loicpoulain]

@lgl88911, It looks interesting, but could you please split it in several commits, at least one for the dts changes, one for the new ov driver and one for the sample.
Thanks for review, the PR will be close and I divided this commit into three:

1. OV7725 driver #30787
   In order to avoid CI fail, After #30787 be merged, the following two branches will make a pull request.

2. mm_swiftio support OV7725, https://github.com/lgl88911/zephyr/tree/mm_swiftio_ov7725

3. sample，https://github.com/lgl88911/zephyr/tree/add_ov7725_sample

No, keep one branch and one PR/MR, don't need to close this one, I just wanted you split your changes in multiple git commits not in multiple branches.

[lgl88911]

@loicpoulain Thanks for your explain, I split it to three commits, Please help review again

[loicpoulain]

Overall, it looks good, just few comments to address.

[MaureenHelm]

Thanks @lgl88911 !

[MaureenHelm]

Is there a reason you can't use i2c_reg_write_byte() instead?

[lgl88911]

Although i2c_reg_write_byte can achieve the same purpose, I hope it is the similar as ov7725_read_reg.

[MaureenHelm]

Replace with i2c_reg_read_byte()

[lgl88911]

OV7725 uses SCCB to communicate. SCCB is similar to I2C, but not exactly the same. When SCCB reads the register, an I2C stop bit is required after the register address of OV7725 is written, and then the read operation can be performed. i2c_reg_read_byte call i2c_write_read, Its implementation lacks a stop bit

{
	struct i2c_msg msg[2];

	msg[0].buf = (uint8_t *)write_buf;
	msg[0].len = num_write;
	msg[0].flags = I2C_MSG_WRITE;

	msg[1].buf = (uint8_t *)read_buf;
	msg[1].len = num_read;
	msg[1].flags = I2C_MSG_RESTART | I2C_MSG_READ | I2C_MSG_STOP;

	return i2c_transfer(dev, msg, 2, addr);
}

[loicpoulain]

Would be nice to add the SCCB explanation as an inline comment.

[lgl88911]

Thanks for suggest, Added it.

[lgl88911]

@MaureenHelm Can you help review again,Thanks