Hardware is a late 2015 11" Macbook Air. The facetimehd-kmp-default package was
installed by default and I installed the facetimehd-firmware manually, despite
this the driver fails to load and the camera is not detected as a device.

[I] clayton@s-169-232-95-114 ~> dmesg -w | grep facetimehd
[    2.934906] [  T349] facetimehd 0000:02:00.0: Found FaceTime HD camera with
device id: 1570
[    2.937304] [  T349] facetimehd 0000:02:00.0: Setting 64bit DMA mask
[    2.958735] [  T349] facetimehd 0000:02:00.0: S2 PCIe link init succeeded
[    2.958770] [  T349] facetimehd 0000:02:00.0: Refclk: 25MHz (0xa)
[    2.968787] [  T349] facetimehd 0000:02:00.0: PLL reset finished
[    2.968793] [  T349] facetimehd 0000:02:00.0: Waiting for S2 PLL to lock at
450 MHz
[    2.968808] [  T349] facetimehd 0000:02:00.0: S2 PLL is locked after 10 us
[    2.978828] [  T349] facetimehd 0000:02:00.0: S2 PLL is in bypass mode
[    2.998898] [  T349] facetimehd 0000:02:00.0: DDR40 PHY PLL locked on safe
settings
[    2.998916] [  T349] facetimehd 0000:02:00.0: STRAP valid
[    2.998917] [  T349] facetimehd 0000:02:00.0: Configuring DDR PLLs for 450
MHz
[    2.998925] [  T349] facetimehd 0000:02:00.0: DDR40 PLL is locked after 0 us
[    2.998935] [  T349] facetimehd 0000:02:00.0: First DDR40 VDL calibration
completed after 2 us
[    2.998943] [  T349] facetimehd 0000:02:00.0: Second DDR40 VDL calibration
completed after 1 us
[    2.998944] [  T349] facetimehd 0000:02:00.0: Using step size 144
[    2.998950] [  T349] facetimehd 0000:02:00.0: VDL set to: coarse=0x10008,
fine=0x10119
[    2.998955] [  T349] facetimehd 0000:02:00.0: Virtual VTT enabled
[    3.019479] [  T349] facetimehd 0000:02:00.0: S2 DRAM memory address:
0x22159559
[    3.019496] [  T349] facetimehd 0000:02:00.0: Rewrite DDR mode registers
succeeded
[    3.019719] [  T349] facetimehd 0000:02:00.0: Full memory verification
succeeded! (0)
[    3.019942] [  T349] facetimehd 0000:02:00.0: Direct firmware load for
facetimehd/firmware.bin failed with error -2
[    3.020079] [  T349] facetimehd 0000:02:00.0: probe with driver facetimehd
failed with error -2

I force reinstalled both and rebooted but still saw the same behavior.

additional context:
uname -a
Linux localhost.localdomain 6.9.1-1-default #1 SMP PREEMPT_DYNAMIC Fri May 17
11:59:46 UTC 2024 (0c0b0b5) x86_64 x86_64 x86_64 GNU/Linux