[PATCH v4 0/3] misc: fastrpc: fix ADSP duplicate session creation

[Vinayak Katoch]

For ADSP, only a limited number of FastRPC context banks (CBs) are
available. Each CB supports a single session, which means only a few
processes can run on ADSP simultaneously. If all sessions are consumed
by fastrpc daemons, no session remains available when a user application
starts, causing the application to fail.

To work around this, some DT set:
  qcom,nsessions = <5>;
which duplicated sessions inline during context bank initialisation.
Upstream feedback indicated that this policy does not belong in DT and
should be handled at the driver level instead.

This series iterates over CB child nodes directly and synchronously,
replacing of_platform_populate(), and moves the ADSP session duplication
to the driver. The qcom,nsessions binding is deprecated in the same
series.

Signed-off-by: Vinayak Katoch <vinayak.katoch@xxxxxxxxxxxxxxxx>
---
Changes in v4:
- Rebased on latest linux-next (a8406e6c0b79, 2026-08-25)
- Link to v3: https://lore.kernel.org/r/20260824-dup-sessions-v3-0-4b019def4e0b@xxxxxxxxxxxxxxxx

Changes in v3:
- Add patch to fix async probe race with of_platform_populate().
- Rename fastrpc_cb_probe() to fastrpc_cb_init().
- Reorder series: sync fix, nsessions, binding.
- Collect Reviewed-by tags.
- Link to v2: https://lore.kernel.org/r/20260708-dup-sessions-v2-0-da40f9c98a2b@xxxxxxxxxxxxxxxx

Changes in v2:
- Added patch to deprecate the qcom,nsessions dt-binding.
- Kept the logic unchanged; only split into two patches.
- Link to v1: https://lore.kernel.org/r/20260609-dup-sessions-v1-1-26934abb9fa3@xxxxxxxxxxxxxxxx

---
Vinayak Katoch (3):
      misc: fastrpc: iterate CB nodes manually instead of of_platform_populate
      misc: fastrpc: move ADSP duplicate session creation to the driver
      dt-bindings: misc: qcom,fastrpc: deprecate qcom,nsessions

 .../devicetree/bindings/misc/qcom,fastrpc.yaml     |   2 +
 drivers/misc/fastrpc.c                             | 112 +++++++++------------
 2 files changed, 48 insertions(+), 66 deletions(-)
---
base-commit: a8406e6c0b793ce0788019683837c40855b55995
change-id: 20260609-dup-sessions-ea2acaac1994

Best regards,
-- 
Vinayak Katoch <vinayak.katoch@xxxxxxxxxxxxxxxx>