[PATCH 0/8] media: qcom: camss: add V4L2 subdev streams API support

[Gjorgji . Rosikopulos . gjorgji . rosikopulos]

From: Gjorgji Rosikopulos <gjorgji.rosikopulos@xxxxxxxxxxxxxxxx>

This series adds V4L2 subdev streams API support to the CAMSS driver.

Each subdevice gains streams-aware enable_streams/disable_streams pad
ops alongside the existing legacy (non-streams) subdev ops, guarded by
a new per-instance streams_enable resource flag.

Patches 1-4 add the CSIPHY/CSID mechanism:
 - CSIPHY: passthrough routing, NO_STREAM_MIX/NO_N_TO_1 validation, and
   shared D-PHY lane enable/disable gated on stream-count transitions.
 - CSID: per-source-pad routing (a single sink stream propagated to
   every source pad by default, remappable for multi-VC sensors),
   VC/DT discovery via get_frame_desc, and new hw_ops
   (configure_rx/enable_stream/disable_stream) with a gen2 backend
   implementation.

Patch 5 is a standalone bug fix, independent of the streams API:
camss_link_entities() used to create an all-to-all CSID-to-VFE
crossbar, but SM8250's hardware wiring is a fixed 1:1 pairing
(csid[i] <-> vfe[i]). Enabling a mismatched link (e.g. csid0 -> vfe1)
exposed a media link with no real hardware datapath. Fixed via an
opt-in csid_vfe_fixed_pairing flag, set only for sm8250_resources.

Patches 6-8 complete the mechanism and turn it on for real hardware:
 - VFE: streams-aware pad ops. VFE lines are inherently single-consumer
   (vfe_link_setup() enforces one link per pad), so no refcounting is
   needed there.
 - camss-video: the video device pipeline walk now checks, via
   v4l2_subdev_has_op(), whether the directly-connected subdev supports
   enable_streams/disable_streams; if so it issues a single top-level
   call instead of manually walking the pipeline one subdev at a time
   with .s_stream(). Falls back to the existing legacy path unchanged
   when the remote subdev doesn't support the streams API, so no other
   platform is affected.
 - SM8250: streams_enable is set true on every CSIPHY, CSID, and VFE
   line resource entry, turning the mechanism on for real hardware.
   Every other platform keeps using the legacy non-streams subdev ops,
   so this is a no-op everywhere else.

A practical benefit of the CSID routing change (patch 4) is routing
flexibility for multi-VC sensors: the CSID's routing table maps sink
streams to source pads/streams via userspace-configurable
v4l2_subdev_route entries instead of a fixed pad<->VC assignment, so a
sensor emitting multiple virtual channels can have each VC directed to
a different RDI output (and thus a different VFE line/video node)
with a set_routing call, rather than being constrained to whatever
fixed mapping the driver hardcodes.

When a sink stream is shared by multiple source pads/streams, CSID
only enables the corresponding upstream CSIPHY stream on the first
source stream that needs it, and only disables it once the last
remaining source stream using it is disabled. Enabling or disabling
additional consumers of an already-active shared stream is a no-op
upstream, so no consumer can double-enable or prematurely disable a
stream still in use by another. This also avoids ever hitting v4l2
core's own -EALREADY re-enable gate.

Verified clean with checkpatch --strict. Built, flashed, and tested on
RB5/SM8250 hardware; ran the no-routing capture verification test
across all four CSID/VFE RDI pairs (csid0->vfe0, csid1->vfe1,
csid2->vfe2, csid3->vfe3) at 4056x3040 - all four passed with
correctly-sized frame captures.

Gjorgji Rosikopulos (8):
  media: qcom: camss: Add streams API support for CSIPHY
  media: qcom: camss: Add streams API hw_ops to CSID interface
  media: qcom: camss: Implement CSID streams API hw_ops for gen2
  media: qcom: camss: Add streams API support in CSID subdevice
  media: qcom: camss: Fix CSID-to-VFE all-to-all link crossbar on sm8250
  media: qcom: camss: add streams API support for VFE
  media: qcom: camss: add streams API support in camss-video
  media: qcom: camss: enable streams API on SM8250

 .../platform/qcom/camss/camss-csid-gen2.c     |  59 ++-
 .../media/platform/qcom/camss/camss-csid.c    | 494 +++++++++++++++++-
 .../media/platform/qcom/camss/camss-csid.h    |  45 ++
 .../media/platform/qcom/camss/camss-csiphy.c  | 223 +++++++-
 .../media/platform/qcom/camss/camss-csiphy.h  |   2 +
 drivers/media/platform/qcom/camss/camss-vfe.c | 119 ++++-
 drivers/media/platform/qcom/camss/camss-vfe.h |   1 +
 .../media/platform/qcom/camss/camss-video.c   | 119 ++++-
 drivers/media/platform/qcom/camss/camss.c     |  21 +-
 drivers/media/platform/qcom/camss/camss.h     |   7 +
 10 files changed, 1046 insertions(+), 44 deletions(-)

-- 
2.34.1