This patch series modernizes the OV5647 camera sensor driver by:

1. Converting from private I2C register access functions to the common
   CCI (Camera Control Interface) register access helpers, which
   simplifies the code and provides better error handling.

2. Switching from driver-specific mutex to the sub-device state lock
   and properly implementing v4l2_subdev_init_finalize() lifecycle.

3. Converting from the legacy s_stream callback to the new
   enable_streams/disable_streams operations to align with current
   V4L2 subsystem standards.

I tested each patch on a Raspberry Pi 5 using the following commands:

rpicam-jpeg --output test.jpg
rpicam-still -o long_exposure.jpg --shutter 100000000 --gain 1 --awbgains 1,1 --immediate

Changes in V4:

 - In patch 1, have corrected the issue of variables that do not need initialization.
   I have defined a chip ID, dropped all control functions, and now set the
   chip ID directly in the set control, using `cci_update_bits()` instead of
   read + write operations.

 - In patch 2, Use dev_err_probe instead of dev_err

 - In patch 3, have corrected the issue of variables that do not need initialization.

Changes in V3:
https://patchwork.kernel.org/project/linux-media/cover/20251231083924.2657165-1-xiaolei.wang@windriver.com/

 - In patch 1, I replaced cci_multi_reg_write() with regmap_multi_reg_write() and
   fixed OV5647_REG_GAIN at 0x350a. I also replaced the original ret = PTR_ERR(sensor->regmap) with dev_err_probe().

 - In patch 2, I replaced the mutex with v4l2_subdev_lock_and_get_active_state() in s_stream().

 - In patch 3, I replaced err_rpm_put with done, and added the ov5647_stream_stop() function.

Changes in V2:
https://patchwork.kernel.org/project/linux-media/cover/20251229023018.2933405-1-xiaolei.wang@windriver.com/

 - Proper register width definitions
 - Fixed formatting and indentation
 - Error chaining implementation
 - Simplified chip detection logic
 - Clean compilation with -Werror
 - Add a new patch, switch from s_stream to enable_streams and disable_streams callbacks.

Link to V1: https://patchwork.kernel.org/project/linux-media/cover/20251226031311.2068414-1-xiaolei.wang@windriver.com/ 

Xiaolei Wang (3):
  media: i2c: ov5647: Convert to CCI register access helpers
  media: i2c: ov5647: Switch to using the sub-device state lock
  media: i2c: ov5647: switch to {enable,disable}_streams

 drivers/media/i2c/Kconfig  |   1 +
 drivers/media/i2c/ov5647.c | 450 ++++++++++++-------------------------
 2 files changed, 144 insertions(+), 307 deletions(-)

-- 
2.43.0