PROBLEM: Linux 5.5 fails to load firmware for Intel(R) Dual Band Wireless AC 3168

[Stuart Little]

I am on an

Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz

with an Intel wifi card:

Intel(R) Dual Band Wireless AC 3168, REV=0x220

The machine is running Slackware 14.2 with a custom-compiled 5.5 kernel (from source; commit d5226fa6dbae Linux 5.5).

The issue:

Booting into that kernel results in failure to load the wifi card firmware. The relevant dmesg portion is attached (these are all of the lines containing 'iwlwifi'). 

I have checked that it breaks between

def9d2780727 Linux 5.5-rc7 (good)

and

d5226fa6dbae Linux 5.5 (bad)

I will attempt a bisect to track down the precise faulty commit, but this is all I have for now. Please let me know if I can provide more info short of the bisect.

P.S.

I have checked that the very latest commit at the time of this writing (41dcd67e88688afbeb3b2bd23960eed5daec74e7 at Fri Feb 7 20:07:29 EST 2020) is still broken on this machine.
[    1.210208] iwlwifi 0000:02:00.0: loaded firmware version 29.1654887522.0 op_mode iwlmvm
[    1.218505] r8168: This product is covered by one or more of the following patents: US6,570,884, US6,115,776, and US6,327,625.
[    1.223892] r8168  Copyright (C) 2019  Realtek NIC software team <nicfae@xxxxxxxxxxx> 
                This program comes with ABSOLUTELY NO WARRANTY; for details, please see <http://www.gnu.org/licenses/>. 
                This is free software, and you are welcome to redistribute it under certain conditions; see <http://www.gnu.org/licenses/>. 
[    1.230349] xhci_hcd 0000:00:14.0: xHCI Host Controller
[    1.230500] xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 1
[    1.231808] xhci_hcd 0000:00:14.0: hcc params 0x200077c1 hci version 0x100 quirks 0x0000000081109810
[    1.232080] xhci_hcd 0000:00:14.0: cache line size of 64 is not supported
[    1.232486] hub 1-0:1.0: USB hub found
[    1.232640] hub 1-0:1.0: 12 ports detected
[    1.233280] xhci_hcd 0000:00:14.0: xHCI Host Controller
[    1.233440] xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 2
[    1.233690] xhci_hcd 0000:00:14.0: Host supports USB 3.0 SuperSpeed
[    1.233883] AVX2 version of gcm_enc/dec engaged.
[    1.234067] AES CTR mode by8 optimization enabled
[    1.234279] hub 2-0:1.0: USB hub found
[    1.234446] hub 2-0:1.0: 6 ports detected
[    1.277853] iwlwifi 0000:02:00.0: Detected Intel(R) Dual Band Wireless AC 3168, REV=0x220
[    1.297761] iwlwifi 0000:02:00.0: Can't parse phy_sku in B0, empty sections
[    1.297916] iwlwifi 0000:02:00.0: Failed to read NVM: -61
[    1.298063] iwlwifi 0000:02:00.0: Collecting data: trigger 16 fired.
[    1.299371] iwlwifi 0000:02:00.0: Start IWL Error Log Dump:
[    1.299521] iwlwifi 0000:02:00.0: Status: 0x00000040, count: 6
[    1.299673] iwlwifi 0000:02:00.0: Loaded firmware version: 29.1654887522.0
[    1.299829] iwlwifi 0000:02:00.0: 0x00000084 | NMI_INTERRUPT_UNKNOWN       
[    1.299983] iwlwifi 0000:02:00.0: 0x000002F0 | trm_hw_status0
[    1.300132] iwlwifi 0000:02:00.0: 0x00000000 | trm_hw_status1
[    1.300291] iwlwifi 0000:02:00.0: 0x0004171E | branchlink2
[    1.300442] iwlwifi 0000:02:00.0: 0x000446B2 | interruptlink1
[    1.300595] iwlwifi 0000:02:00.0: 0x000446B2 | interruptlink2
[    1.300747] iwlwifi 0000:02:00.0: 0x00000000 | data1
[    1.300895] iwlwifi 0000:02:00.0: 0x00000080 | data2
[    1.301041] iwlwifi 0000:02:00.0: 0x07030000 | data3
[    1.301190] iwlwifi 0000:02:00.0: 0x00000000 | beacon time
[    1.301341] iwlwifi 0000:02:00.0: 0x00001451 | tsf low
[    1.301491] iwlwifi 0000:02:00.0: 0x00000000 | tsf hi
[    1.301642] iwlwifi 0000:02:00.0: 0x00000000 | time gp1
[    1.301793] iwlwifi 0000:02:00.0: 0x00001452 | time gp2
[    1.301943] iwlwifi 0000:02:00.0: 0x00000009 | uCode revision type
[    1.302094] iwlwifi 0000:02:00.0: 0x0000001D | uCode version major
[    1.302245] iwlwifi 0000:02:00.0: 0x62A39462 | uCode version minor
[    1.302397] iwlwifi 0000:02:00.0: 0x00000220 | hw version
[    1.302548] iwlwifi 0000:02:00.0: 0x00C89200 | board version
[    1.302701] iwlwifi 0000:02:00.0: 0x00110188 | hcmd
[    1.302852] iwlwifi 0000:02:00.0: 0x00022000 | isr0
[    1.303003] iwlwifi 0000:02:00.0: 0x00000000 | isr1
[    1.303152] iwlwifi 0000:02:00.0: 0x00000002 | isr2
[    1.303301] iwlwifi 0000:02:00.0: 0x004000C0 | isr3
[    1.303448] iwlwifi 0000:02:00.0: 0x00000000 | isr4
[    1.303596] iwlwifi 0000:02:00.0: 0x00110188 | last cmd Id
[    1.303746] iwlwifi 0000:02:00.0: 0x00000000 | wait_event
[    1.303897] iwlwifi 0000:02:00.0: 0x00000080 | l2p_control
[    1.304047] iwlwifi 0000:02:00.0: 0x00000000 | l2p_duration
[    1.304197] iwlwifi 0000:02:00.0: 0x00000000 | l2p_mhvalid
[    1.304346] iwlwifi 0000:02:00.0: 0x00000000 | l2p_addr_match
[    1.304496] iwlwifi 0000:02:00.0: 0x00000007 | lmpm_pmg_sel
[    1.304652] iwlwifi 0000:02:00.0: 0x16070617 | timestamp
[    1.304798] iwlwifi 0000:02:00.0: 0x00341018 | flow_handler
[    1.304966] iwlwifi 0000:02:00.0: Fseq Registers:
[    1.305139] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_ERROR_CODE
[    1.305306] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_TOP_INIT_VERSION
[    1.305475] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_CNVIO_INIT_VERSION
[    1.305652] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_OTP_VERSION
[    1.305822] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_TOP_CONTENT_VERSION
[    1.305995] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_ALIVE_TOKEN
[    1.306175] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_CNVI_ID
[    1.306356] iwlwifi 0000:02:00.0: 0x00000000 | FSEQ_CNVR_ID
[    1.306524] iwlwifi 0000:02:00.0: 0x00000000 | CNVI_AUX_MISC_CHIP
[    1.306695] iwlwifi 0000:02:00.0: 0x00000000 | CNVR_AUX_MISC_CHIP
[    1.306870] iwlwifi 0000:02:00.0: 0x00000000 | CNVR_SCU_SD_REGS_SD_REG_DIG_DCDC_VTRIM
[    1.307135] iwlwifi 0000:02:00.0: 0x00000000 | CNVR_SCU_SD_REGS_SD_REG_ACTIVE_VDIG_MIRROR
[    1.307402] iwlwifi 0000:02:00.0: Firmware not running - cannot dump error
[    1.319717] iwlwifi 0000:02:00.0: Failed to run INIT ucode: -61