Re: [PATCH 06/13] media: v4l2-subdev: Mark both streams of a route enabled

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

On Fri, Jun 20, 2025 at 01:18:57AM +0300, Laurent Pinchart wrote:
> On Thu, Jun 19, 2025 at 06:34:25PM +0000, Sakari Ailus wrote:
> > On Thu, Jun 19, 2025 at 07:56:04PM +0300, Laurent Pinchart wrote:
> > > On Thu, Jun 19, 2025 at 11:15:39AM +0300, Sakari Ailus wrote:
> > > > Streams are stored in sink-source pairs in sub-device state.
> > > 
> > > Is it really this simple ? Don't we support for instance stream merging
> > > where two streams on possibly different sink pads are routed to a single
> > > stream on a source pad ?
> > 
> > As far as I'm concerned, yes. Each route has a sink and a source pad, you
> > may have multiple routes from a pad or to a pad, but these are all separate
> > routes. The UAPI as well as v4l2-subdev.c is aligned with this and I
> > wouldn't expect it to be otherwise.
> 
> Should we then refactor v4l2_subdev_stream_configs to contain a list of
> route configs, with each route config containing two stream configs, one
> for the sink pad and one for the source pad ? We would still have
> duplicated entries when multiple routes originate from or end at the
> same pad/stream, but the data structures would be more explicit and we
> would rely less on the fact that each route has a pair of consecutive
> stream configs.

Most of the code dealing with stream configurations works on either sink or
source pads and the current data structure makes that code more simple. I
think this was probably a factor why Tomi wrote it like this.

Tomi, any comment on this?

> 
> > I'd like to have Tomi's view on this, too.
> > 
> > > > When a stream
> > > > was marked enabled (or disabled), only the state of one end of the stream
> > > > was modified, leaving the stream in an incoherent state. Mark both ends of
> > > > the stream enabled (or disabled).
> > 
> > This should discuss "route" in fact, not "stream".
> 
> That would make it a bit clearer.

I'll fix this for v2.

-- 
Regards,

Sakari Ailus