WCN7850 on Surface Pro 11: no board-2.bin entry, firmware reports no board ID

[Dale Whinham]

Hi,

The WCN7850 in the Microsoft Surface Pro 11 (X1E80100) finds no entry in
ath12k/WCN7850/hw2.0/board-2.bin and falls through to the board.bin
API-1 path. I am looking for some advice on what the correct fix is.

The device reports:

  chip_id 0x2 chip_family 0x4 board_id 0xff soc_id 0x40170200
  PCI 17cb:1107, subsystem 17cb:1107

A debug print in ath12k_qmi_request_target_cap() shows board_info is
absent from the capability response:

  cap_resp board_info_valid 0 chip_info_valid 1 soc_info_valid 1

chip_info and soc_info are present, so the response itself is fine. The
0xff is ATH12K_BOARD_ID_DEFAULT, substituted by the driver.

The names ath12k then looks up are:

  bus=pci,vendor=17cb,device=1107,subsystem-vendor=17cb,subsystem-device=1107,qmi-chip-id=2,qmi-board-id=255
  bus=pci,qmi-chip-id=2,qmi-board-id=255

Neither exists in board-2.bin (linux-firmware-atheros 20260810-2).
The only subsystem-device=1107 entries there are qmi-board-id=44 and
qmi-board-id=82.

Using a different entry from the same board-2.bin as board.bin does work
(i.e. extract using ath12k-bdencoder and rename). I have been running
the subsystem-device=3378, qmi-board-id=255 entry, which associates and
passes traffic normally. That may be another board's data rather than a fix,
but it does suggest the firmware accepts entries from this
linux-firmware release, and that what is missing is an entry under a
name this device derives.

I also checked what Windows provides:

  - Windows loads bdwlan.elf on this machine, via the catch-all
    PCI\VEN_17CB&DEV_1107 section of qcwlanhmt8380.inf. The same file
    appears in that driver for several other 8380 devices, so it is not
    Surface-specific.

  - That file fails against the upstream firmware with -110 ("qmi failed
    to load bdf file"). It works if the Windows firmware and PHY ucode
    are used with it, so the data is valid for the part but looks tied
    to the firmware version:

    Windows:  WLAN.HMT.1.1.c5-00310-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1
    upstream: WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3

What is the right way to give this device board data? Happy to provide
further info or test patches.

Thanks,
Dale