Hi Sakari, On Fri, Jun 02, 2023 at 01:10:40PM +0000, Sakari Ailus wrote: > On Fri, Jun 02, 2023 at 12:46:50PM +0300, Laurent Pinchart wrote: > > On Fri, Jun 02, 2023 at 12:44:12PM +0300, Laurent Pinchart wrote: > > > On Mon, May 08, 2023 at 03:24:10PM +0300, Sakari Ailus wrote: > > > > On Mon, May 08, 2023 at 01:14:07PM +0300, Tomi Valkeinen wrote: > > > > > On 06/05/2023 00:52, Sakari Ailus wrote: > > > > > > Take the new INTERNAL_SOURCE pad flag into account in validating routing > > > > > > IOCTL argument. Effectively this is a SINK pad in this respect. Due to the > > > > > > union there's no need to check for the particular name. > > > > > > > > > > What union? The one you add in the next patch? > > > > > > > > Oops. I think we can reorder the patches. > > > > > > > > > As a concept the internal source pads sound good, and they work in practice > > > > > in my tests. But this union is what grates me a bit. We have a flag, > > > > > MEDIA_PAD_FL_INTERNAL_SOURCE, which tells which field of the union to use, > > > > > and then we go and do not use the new union field. Well, and also the > > > > > naming, as we normally have source and sink pads, but now we also have > > > > > internal source pads, which are actually identical to sink pads... > > > > > > > > The union still should be used by the user space. We're testing flags here > > > > and those flags are the same independently of the INTERNAL_SOURCE flag. > > > > > > > > I'm fine by not adding that union though, but for the user space I think > > > > it's better we have it: explaining that the sink_pad has a different > > > > meaning if that flag is set is harder than making it a union member. > > > > > > > > > I understand the idea and reasoning, but the two points above do confuse me > > > > > and I'm sure would confuse others also. > > > > > > > > > > I wonder if it would be less or more confusing to simplify this by just > > > > > adding a MEDIA_PAD_FL_INTERNAL, which could be applied to either a source or > > > > > a sink pad, and would prevent linking to it. The flag would indicate that > > > > > the stream from/to that pad is generated/consumed internally. (I don't know > > > > > when you would need an internal pad to consume data, but... who knows, the > > > > > need might pop up =). > > > > > > > > This is another option. But I envision there will be more compatibility > > > > issues. Although... generally using such hardware requires knowledge of the > > > > device, and we haven't obviously had any support for devices needing this > > > > functionality in the tree. So in the end it might not matter much. > > > > > > > > > That would mean that an "internal sink pad" would generate a data stream, > > > > > i.e. it's a "source", but I think a normal sink pad is almost the same > > > > > anyway: when considering entity's internal routing, the normal sink pad is a > > > > > "source", and the same logic would apply with the internal pads too. > > > > > > > > > > An internal sink pad that generates a stream is a bit more confusing than an > > > > > internal source pad, but I think that confusion is less than the rest of the > > > > > confusion in the code-side that comes with the internal source pads. > > > > > > > > I prefer having the possible sources of the confusion in the framework than > > > > in the drivers. Therefore I think INTERNAL_SOURCE flag is a (slightly) > > > > better option. > > > > > > > > I wonder what Llaurent thinks. > > > > > > I like the idea of a MEDIA_PAD_FL_INTERNAL flag. That's actually how I > > > read patch 1/7, I didn't notice it used MEDIA_PAD_FL_INTERNAL*_SOURCE* > > > :-) > > > > > > We could define MEDIA_PAD_FL_INTERNAL_SOURCE > > > > > > #define MEDIA_PAD_FL_INTERNAL_SOURCE (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_INTERNAL) > > > > One option would be to find terms different from sink and source in this > > case. It would generate less confusion to map (e.g., not a really good > > name) MEDIA_PAD_FL_INTERNAL_PRODUCER to MEDIA_PAD_FL_SINK and to the > > sink_pad field than using MEDIA_PAD_FL_INTERNAL_SOURCE. > > I don't think this helps as you'd still be accessing the sink pad related > fields that are there for another purpose. > > Alternatively I'd have the (plain) INTERNAL flag and drop the union, > without masking or adding compound flags. > > I can switch to that if you promise not to change your mind again. ;-) I'll do my best :-) Could you show the impact (if any) it would have on drivers when accessing the routing fields ? > > > but I'm not sure it would be less confusing. > > > > > > Regarding isolating the sources of confusion in the framework rather > > > than spreading them through drivers, I can't disagree, but I think that, > > > for raw camera sensors at least, the best option would be to create a > > > new camera sensor object with a much more tailored API than v4l2_subdev > > > (and of course wrapping that new object in a v4l2_subdev in the > > > framework). This won't address the other types of drivers, but I'm not > > > sure we'll get any in the foreseable future. -- Regards, Laurent Pinchart
