"Failed to initialize GPU, declaring it wedged!" after drm-next added to Linus' master

Dell XPS 7390 2-in-1, i7-1065G7 CPU, running a recent Mesa master branch. I normally have i915 module loaded as:

options i915 enable_guc=2 to enable HuC.

I run Linus' master, and today drm-next (477f70cd2a6, drm-next-2021-08-31-1) was merged in. I'm up on the latest(?) linux-firmware (6f5aada830d69e9e0). and have no GPU:

<3>[    9.734916][  T453] i915 0000:00:02.0: GuC initialization failed -110
<3>[    9.734925][  T453] i915 0000:00:02.0: Enabling uc failed (-5)
<3>[    9.734927][  T453] i915 0000:00:02.0: Failed to initialize GPU, declaring it wedged!
<5>[    9.735274][  T453] i915 0000:00:02.0: [drm:intel_gt_set_wedged_on_init [i915]] CI tainted:0x9 by intel_gt_init+0x233/0xaf0 [i915]
<6>[    9.893989][  T453] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 0
<6>[    9.897206][  T453] ACPI: video: Video Device [GFX0] (multi-head: yes  rom: no  post: no)
<6>[    9.897666][  T453] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input18
<6>[    9.897817][  T453] snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
<6>[    9.932687][  T125] fbcon: i915 (fb0) is primary device
<6>[    9.932784][  T125] Console: switching to colour frame buffer device 240x75
<6>[    9.939313][  T125] i915 0000:00:02.0: [drm] fb0: i915 frame buffer device

Reverting that merge gets me back and restores HW acceleration in Mesa.

So, do I just wait for the latest GuC to be pushed, or is this a symptom of a larger issue (I didn't think IceLake mobile CPUs were capable of GuC Submission)?

Oh, these are my FW versions (before the drm-next merge):

[   10.291899] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/icl_dmc_ver1_09.bin (v1.9)
[   10.436810] i915 0000:00:02.0: [drm] GuC firmware i915/icl_guc_49.0.1.bin version 49.0 submission:disabled
[   10.436815] i915 0000:00:02.0: [drm] HuC firmware i915/icl_huc_9.0.0.bin version 9.0 authenticated:yes