Re: [PATCH 0/3] media: v4l: async: add helper API v4l2_async_pad_init_and_register_subdev()

[Frank Li <Frank.li@nxp.com>]

On Fri, Feb 20, 2026 at 10:01:01AM +0100, Michael Riesch wrote:
> Hi Frank,
>
> Thanks for your patches.
>
> On 2/10/26 22:42, Frank Li wrote:
> > Add the helper API v4l2_async_pad_init_and_register_subdev(), which
> > combines media_entity_pads_init(), v4l2_subdev_init_finalize(), and
> > v4l2_async_register_subdev() into a single call.
>
> I think this is a good idea, but can you extend that to offer variants
> for v4l2_async_register_subdev_sensor and v4l2_device_register_subdev too?
>
> The function names are awfully long, though. Can we call this
>     media_register_subdev{_async,_sensor,}
> maybe?

How about media_async_register_subdev()? which basic align other API
naming. I want to add more helper APIs.

drivers/media/platform/synopsys/dw-mipi-csi2rx.c have about 600 lines code
but related hardware register codes are below 20 line, only few registers.

I just post this simple version to gather feedback from maintainers and
reviewers on the overall approach.

Frank

>
> Best regards,
> Michael
>
> >
> > Reduce code duplication and simplify error handling in drivers.
> >
> > Only change dwc and cdns. If agree add API, more driver can be simplified.
> >
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> > Frank Li (3):
> >       media: v4l: async: add helper API v4l2_async_pad_init_and_register_subdev()
> >       media: synopsys: Use v4l2_async_pad_init_and_register_subdev() to simplify code
> >       media: cadence: cdns-csi2rx: Use v4l2_async_pad_init_and_register_subdev() to simplify code
> >
> >  drivers/media/platform/cadence/cdns-csi2rx.c     | 18 ++++----------
> >  drivers/media/platform/synopsys/dw-mipi-csi2rx.c | 15 +++---------
> >  drivers/media/v4l2-core/v4l2-async.c             | 30 ++++++++++++++++++++++++
> >  include/media/v4l2-async.h                       | 18 ++++++++++++++
> >  4 files changed, 55 insertions(+), 26 deletions(-)
> > ---
> > base-commit: bc0bfce7d0f8204e0bbadcee72e87ad9ec105c73
> > change-id: 20260210-v4l2_init_register-0e6d0adcfa21
> >
> > Best regards,
> > --
> > Frank Li <Frank.Li@nxp.com>
> >
>