Hi Hans, On Sunday, 4 February 2018 15:16:26 EET Hans Verkuil wrote: > On 02/04/2018 02:13 PM, Laurent Pinchart wrote: > > On Sunday, 4 February 2018 15:06:42 EET Hans Verkuil wrote: > >> Hi Mauro, > >> > >> I'm working on adding proper compliance tests for the MC but I think > >> something is missing in the G_TOPOLOGY ioctl w.r.t. pads. > >> > >> In several v4l-subdev ioctls you need to pass the pad. There the pad is > >> an index for the corresponding entity. I.e. an entity has 3 pads, so the > >> pad argument is [0-2]. > >> > >> The G_TOPOLOGY ioctl returns a pad ID, which is > 0x01000000. I can't use > >> that in the v4l-subdev ioctls, so how do I translate that to a pad index > >> in my application? > >> > >> It seems to be a missing feature in the API. I assume this information is > >> available in the core, so then I would add a field to struct media_v2_pad > >> with the pad index for the entity. > >> > >> Next time we add new public API features I want to see compliance tests > >> before accepting it. It's much too easy to overlook something, either in > >> the design or in a driver or in the documentation, so this is really, > >> really needed IMHO. > > > > I agree with you, and would even like to go one step beyond by requiring > > an implementation in a real use case, not just in a compliance or test > > tool. > > > > On the topic of the G_TOPOLOGY API, it's pretty clear it was merged too > > hastily. We could try to fix it, but given all the issues we haven't > > solved yet, I believe a new version of the API would be better. > > It's actually not too bad as an API speaking as an end-user. It's simple and > efficient. But this pad issue is a real problem. We have other issues such as connector support and entities function vs. types that we have never solved. The G_TOPOLOGY ioctl moves in the right direction but has clearly been merged too early. It might be possible to fix it, I haven't checked yet, but I really don't want to see this mistake being repeated in the future. -- Regards, Laurent Pinchart
