Hi Hans, On 12/09/2019 08:48, Hans Verkuil wrote: > Hi all, > > I am increasingly unhappy about the choice of /dev/videoX for metadata devices. > > It is confusing for end-users (especially w.r.t. the common uvc driver) and > if we want to change this, then we need to do it soon. > > This patch https://patchwork.linuxtv.org/patch/58693/ adds a new VFL_TYPE_METADATA > so at least drivers can now explicitly signal that they want to register a > metadata device. > > This also makes it possible to add a kernel config option that allows you > to select whether you want metadata devices to appear as videoX or v4l-metaX. > I would prefer to set it to v4l-metaX by default. I think I prefer this separation (v4l-metaX). Having metadata as a (separate) videoX seemed odd to me - but I only saw/was affected by the metadata topics when it was too late it seemed ... > We can also consider backporting this to the stable/long-term kernels. > > Metadata capture was introduced in 4.12 for the vsp1 driver, in 4.16 for the > uvc driver and in 5.0 for the staging ipu3 driver. > > Does someone remember the reason why we picked /dev/videoX for this in the > first place? I've wondered why it's not a separate queue on the same video device - much like we have multiple queues for V4L2-M2M devices .... The data is relative to the same frames coming from the main queue right ? That might have been awkward to express through our device type flags though. Anyway, I thought the horse had bolted on this topic ? :-D > Regards, > > Hans > -- Regards -- Kieran
