[PATCH v4 0/3] media: qcom: iris: add multi slice support

[Sachin Kumar Garg <sachin.garg@oss.qualcomm.com>]

This series adds support for multi-slice encoding in the Qualcomm Iris
driver.

Multi-slice mode allows encoding a single frame into multiple slices,
which can improve error resilience and enable parallel processing.
The feature supports two slice modes:
- MAX_MB mode: slices are created based on macroblock count, controlled
  via V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB
- MAX_BYTES mode: slices are created based on byte size, controlled via
  V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES

Clients can enable slice mode using the V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE
control.

Patch 1 is a prerequisite fix: iris_set_stage() computes a work_mode
but never caches it back into inst->fw_caps[STAGE].value, leaving
buffer-size and clock-frequency calculations based on a stale value.

Patch 2 is another prerequisite fix: iris_set_stage() currently always
selects STAGE_2 work mode for encoder sessions, but CBR rate control
requires STAGE_1. This is fixed by forcing STAGE_1 when BITRATE_MODE is
set to CBR.

Patch 3 adds the multi-slice support itself for Iris HFI Gen2 based
targets (qcs8300, sm8550 and other SM8550-derived targets).
Support for HFI Gen1 targets will be added in a follow-up series.

This series has been verified with GST level testing.
Command used:
gst-launch-1.0 -v videotestsrc ! video/x-raw,format=NV12, \
width=1280,height=720,framerate=30/1 ! v4l2h264enc output-io-mode=4 |
capture-io-mode=4 extra-controls="controls,video_bitrate_mode=1, \
slice_partitioning_method=1,number_of_mbs_in_a_slice=460;" \
! filesink location=/opt/test_enc.h264

Changes in v4:
- Split out a new prerequisite patch (patch 1) to cache the computed
  work_mode into inst->fw_caps[STAGE].value in iris_set_stage(), since
  this fixes a pre-existing bug independent of the CBR change and
  needed its own Fixes tag.
- Deduplicated the per-target slice capability limits that were
  previously repeated identically across platform_inst_cap_qcs8300 and
  platform_inst_cap_sm8550. Introduced struct platform_inst_slice_caps
  and moved it to iris_platform_data (one level up from
  platform_inst_caps), since all Iris HFI Gen2 targets share the same
  encoder capability table and hence the same slice limits; a single
  default_slice_caps_vpu3x instance is now referenced by all Gen2
  platforms.
- Link to v3: https://lore.kernel.org/r/20260721-iris_multi_slice-v3-0-adc61a687e7e@oss.qualcomm.com

Changes in v3:
- Patch 1 (force stage 1 work mode for CBR RC): cache the computed
  work_mode into inst->fw_caps[STAGE].value so buffer-size and
  clock-frequency calculations stay consistent with what is actually
  configured on firmware.
- Patch 2 (multi-slice support):
  - Use inst->hfi_rc_type instead of the raw V4L2 BITRATE_MODE value
    when validating/deriving slice parameters, avoiding a mismatch
    between V4L2 and firmware rate-control enums.
  - Round up (instead of truncate) when computing the minimum
    MAX_MB and MAX_BYTES slice size floors, so the hardware's
    max-slices-per-frame limit is never exceeded.

Changes in v2:
- Added a prerequisite patch to force STAGE_1 work mode for CBR rate
  control on the encoder, required for multi-slice encoding to work
  correctly.
- Addressed review comments on the multi-slice patch (updated commit
  subject and description).

Signed-off-by: Sachin Kumar Garg <sachin.garg@oss.qualcomm.com>
---
Sachin Kumar Garg (3):
      media: iris: cache work mode after computing it in iris_set_stage
      media: iris: force stage 1 work mode for CBR RC on encoder
      media: iris: add support for multi_slice in iris encoder

 drivers/media/platform/qcom/iris/iris_ctrls.c      | 84 ++++++++++++++++++++++
 drivers/media/platform/qcom/iris/iris_ctrls.h      |  1 +
 drivers/media/platform/qcom/iris/iris_hfi_gen2.c   | 33 ++++++++-
 .../platform/qcom/iris/iris_hfi_gen2_defines.h     |  2 +
 .../platform/qcom/iris/iris_platform_common.h      | 16 +++++
 .../media/platform/qcom/iris/iris_platform_vpu3x.c | 17 +++++
 6 files changed, 152 insertions(+), 1 deletion(-)
---
base-commit: 42f83a32259a82c4481d3cccf560c3bfeb32c892
change-id: 20260716-iris_multi_slice-5647287a9563

Best regards,
-- 
Sachin Kumar Garg <sachin.garg@oss.qualcomm.com>