Re: [RFC PATCH v3 0/2] media: i2c: Add onsemi AR0234 camera sensor driver

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Fri, Mar 06, 2026 at 01:36:12PM +0300, Alexander Shiyan wrote:
> This series adds a driver for the onsemi AR0234 CMOS image sensor.
> The AR0234 is a 1/2.6-inch global-shutter sensor with a 1940x1220
> pixel array, capable of 1920x1200 resolution at up to 120 fps.
> It supports MIPI CSI-2 output with 1 to 4 data lanes, raw Bayer
> (8/10-bit) and monochrome formats, as well as DPCM 10->8 compression.
> 
> The driver has been tested with 2 and 4 lanes on an ARM64 Rockchip
> RK3568 platform with a 27 MHz external clock. Both 8-bit and 10-bit
> raw Bayer modes are functional.
> 
> Notes:
> - 1-lane mode is currently disabled; attempts to use it produced no
>   valid image. Further investigation is needed.

That's a fair limitation for the time being.

> - The driver uses a private streaming flag to protect cropping changes
>   during streaming. Is this the recommended approach, or should we
>   rely solely on the subdev state?

Is there a reason not to use v4l2_subdev_is_streaming() ?

> - The DPCM (10->8 compression) mode is included in the code but could
>   not be tested due to lack of suitable hardware; any testing help
>   would be appreciated.

The only upstream drivers that implement DPCM support are omap3isp and
atomisp. It will be difficult to get hold of a hardware setup that
include an AR0234 :-(

> Changes since v2:
> - Added devicetree binding documentation for the onsemi AR0234 sensor.
> - Added support for 8-bit raw Bayer output (verified working).
> - Added DPCM 10->8 compression mode (untested, included for
>   completeness).
> - Reworked mode handling: each mode now specifies input/output bpp,
>   DPCM flag, MIPI data type, and link frequency index.
> - Reworked link frequency handling: the driver now accepts any valid
>   link frequencies from the device tree. It expects two frequencies -
>   one for 8-bit mode and one for 10-bit mode - but does not enforce
>   a fixed set; frequencies are validated by attempting PLL calculation.
>   This makes the driver compatible with a wider range of system
>   configurations.
> - Updated ar0234_calculate_pll() to use a temporary structure and
>   update cached PLL only on success.
> 
> Changes since v1:
> - Improved error handling: use cci_write() with &ret chaining for
>   sequential register writes, as suggested by Isaac Scott.
> - Refactored format and cropping support:
>   Replaced static format list with dynamic cropping rectangle
>   (struct v4l2_rect crop).
>   Implemented get_selection and set_selection for V4L2_SEL_TGT_CROP,
>   allowing runtime selection of the active sensor area.
> - Migrated to modern streaming model: replaced s_stream with
>   enable_streams/disable_streams using v4l2_subdev_s_stream_helper.
> - Corrected blanking constants: replaced ambiguous AR0234_HBLANK_DEF
>   with AR0234_LINE_LENGTH_PCK_MIN; updated min/max ranges.
> - Added ACPI match table (untested).
> - Style fixes.
> 
> Any further comments or test results would be greatly appreciated.
> 
> Alexander Shiyan (2):
>   dt-bindings: media: i2c: Add onsemi AR0234 image sensor binding
>   media: i2c: Add onsemi AR0234 image sensor driver
> 
>  .../bindings/media/i2c/onnn,ar0234.yaml       |  109 ++
>  drivers/media/i2c/Kconfig                     |   12 +
>  drivers/media/i2c/Makefile                    |    1 +
>  drivers/media/i2c/ar0234.c                    | 1309 +++++++++++++++++
>  4 files changed, 1431 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/onnn,ar0234.yaml
>  create mode 100644 drivers/media/i2c/ar0234.c

-- 
Regards,

Laurent Pinchart