Hi Laurent,
On Sat, 2021-01-09 at 03:09 +0200, Laurent Pinchart wrote:
> Could you elaborate a little bit here ? We don't have an API to
> explicitly enumerate supported interlacing types. This can be done by
> calling VIDIOC_TRY_FMT with all field types and see which ones are
> supported. You can still do so with the MC-based API, the video node
> will return from VIDIOC_TRY_FMT the interlacing types intrinsicly
> supported by the video node, and you can query from the source subdev
> the interlacing types supported by the source. Userspace can then
> combine the information to find what is supported.
The i.MX6 CSI always captures whole frames, so SEQ_TB or SEQ_BT at its
source pad.
The IDMAC supports "interlaced scan" of SEQ_TB into INTERLACED_TB and
SEQ_BT into INTERLACED_BT when writing to memory. It can't change the
field timing order (BT <-> TB) as that was already decided at the CSI.
So for capture of interlaced material, the video device currently allows
either SEQ_TB and INTERLACED_TB or SEQ_BT and INTERLACED_BT, depending
on which field order is configured at the CSI source pad.
See d969291d8479 ("media: imx: Fix field negotiation") for details.
regards
Philipp
