[v2,0/6] media: v4l: add support for Virtual Channel IDs

Message

Cosmin Tanislav Feb. 20, 2025, 11:08 p.m. UTC

Multi-camera systems often have issues with receiving video streams
from multiple cameras at the same time because the cameras use the same
Virtual Channel IDs.

CSI bridges might not support remapping the Virtual Channel IDs, making
it impossible to receive the separate video streams at the same
time, while the CSI receiver is able to de-mux streams based on VC IDs.

Cameras sometimes have support for changing the VC IDs they output
themselves.

For a practical example, GMSL2 deserializer chips do not support VC ID
remapping in tunnel mode, and neither do the serializers. Allowing the
cameras to have their VC IDs configured would allow multi-camera setups
to use tunnel mode.

Add support for specifying these Virtual Channel IDs in Video Interface
Endpoints.

Add support for parsing VC IDs in v4l2_fwnode_endpoint_parse().
This allows us to retrieve the specified VC IDs in camera drivers and
configure the hardware to use them.

The supported values are 0 to 3, with a maximum of 4 values.
Although the CSI-2 specification allows for up to 32 virtual channels,
most hardware doesn't support more than 4. This can be extended later
if need be.

The driver must validate the number of VC IDs and the VC IDs
themselves.

Add an example implementation for IMX219.

V2:
 * goto err_rpm_put on failure to configure VC ID in imx219, and print
   error

Cosmin Tanislav (5):
  dt-bindings: media: video-interfaces: add support for Virtual Channel
    IDs
  media: v4l: fwnode: parse Virtual Channel IDs for CSI2 buses
  dt-bindings: media: imx219: add support for Virtual Channel IDs
  media: i2c: imx219: pass format's code to imx219_get_format_bpp()
  media: i2c: imx219: implement configurable VC ID

Laurent Pinchart (1):
  media: i2c: imx219: Report streams using frame descriptors

 .../devicetree/bindings/media/i2c/imx219.yaml |  2 +
 .../bindings/media/video-interfaces.yaml      | 11 ++++
 drivers/media/i2c/imx219.c                    | 56 ++++++++++++++++++-
 drivers/media/v4l2-core/v4l2-fwnode.c         | 15 +++++
 include/media/v4l2-mediabus.h                 |  5 ++
 5 files changed, 86 insertions(+), 3 deletions(-)