Re: [PATCH v7 7/8] media: raspberrypi: Add support for PiSP BE

[Sakari Ailus <sakari.ailus@iki.fi>]

Hi Laurent,

On Mon, May 27, 2024 at 04:19:11AM +0300, Laurent Pinchart wrote:
> > One API-based solution could be moving the IOCTL interface to MC device
> > node only. This wouldn't be a small change so I'm not proposing doing that
> > now.
> 
> I think we could also use the request API. It is a bit more cumbersome
> to use from a userspace point of view, but this driver is meant to be
> used from libcamera, so we can isolate applications from the extra
> burden.
> 
> We will need to add support for formats in the request API (or rather
> for requests in the format ioctls).
> 
> From a kernel point of view, the helpers used by the codec drivers may
> not be suitable for ISP drivers, but I don't think it would be very
> difficult to implement other helpers is needed, isolating the ISP driver
> from the complexity of the request API.
> 
> This doesn't preclude developing a better userspace API with ioctls on
> the MC device node only at a later point. If the above-mentioned kernel
> helpers are done right, transitioning to a new userspace API will have
> minimal impact on drivers.

This is indeed the third feasible option. I agree. The work on the
framework side might not be that much either.

-- 
Regards,

Sakari Ailus