Hi Paul, On Fri, Jun 02, 2023 at 11:39:54AM +0200, Paul Kocialkowski wrote: > Hi, > > (Re-adding folks from the original email, adding Laurent and Hans.) > > On Fri 02 Jun 23, 11:24, Martijn Braam wrote: > > Hi Paul, > > > > That's basically it yes. My software doesn't expect the bridge block, > > because it wasn't there. The pipeline always worked "automatically". > > > > This is the workaround that's been made now it run on newer kernels: > > https://gitlab.com/postmarketOS/megapixels/-/merge_requests/31 > > > > I'm pretty sure format propagation would fix this issue. > > Okay that's good to know. > > To be honest it's still not very clear to me if in-driver format propagation is > a "nice to have" feature or something that all media pipeline drivers are > supposed to implement. For MC-based drivers, in-kernel propagation *inside* subdevs is mandatory, in-kernel propagration *between* subdevs is not allowed. The latter is the responsibility of userspace. For traditional (I'd say legacy, but I know not everybody likes that term :-)) drivers that only expose video device nodes and do not expose subdev nodes to userspace, the driver is responsible for configuring the full pipeline internally based on the S_FMT call on the video nodes only. This isn't applicable to the sun6i-csi driver, as it exposes subdev nodes to userspace. > Anyway I feel like this is not really a regression but a result of the driver > being converted to a newer API. > > Also there's a V4L2_CAP_IO_MC flag which should indicate that the video device > must be controlled via the media controller API instead of being > video-device-centric, but I've seen comments asking not to set the flag even > when MC is used so I'm a bit confused here. Would you have pointers to those comments ? > Perhaps the flag is only required when there is no automatic format > propagation? The flag is more or less required when you expose subdev nodes to userspace. > If anyone has solid answers on these points I'd be happy to read some > clarification (and act accordingly). > > > On 6/2/23 11:16, Paul Kocialkowski wrote: > > > Hi Martijn, > > > > > > On Thu 01 Jun 23, 23:19, Martijn Braam wrote: > > > > It seems like this commit: > > > > > > > > media: sun6i-csi: Add bridge v4l2 subdev with port management > > > > > > > > Has changed the way the media pipeline on a64 devices, in my case the PINE64 > > > > PinePhone works. Since this is an API towards userspace and there's active > > > > applications that use it I think this counts as a regression. > > > Do you have more details on what changed specifically? > > > > > > The commit added a bridge subdev in addition to the video node, which is > > > generally a better description of the CSI hardware and also a necessity > > > to support the ISP data flow. > > > > > > Maybe your userspace application is not configuring the bridge media block with > > > the right format, which results in a mismatch? > > > > > > Some work was started to achieve automatic format propagation, perhaps it > > > would be enough to solve your issue. > > > > > > Cheers, > > > > > > Paul > > > > > > > #regzbot introduced: 0d2b746b1bef73de62d2d311e594a7ffed4ca43 -- Regards, Laurent Pinchart
