Bug#956703: linux-image-5.5: 5.5 kernel seems to break pulseaudio HDMI detection

[Noah Meyerhans <noahm@debian.org>]

On Tue, Apr 14, 2020 at 02:06:30PM +0100, Simon John wrote:
> Booting into 5.5 on Sid gives me no audio out via HDMI.

I can confirm similar HDMI audio breakage with 5.5.13 on a Thinkpad X1
Carbon (gen2) with the following audio devices:

00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 0b)
        Subsystem: Lenovo Haswell-ULT HD Audio Controller
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 56
        Region 0: Memory at f0530000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd_hda_intel

00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
        Subsystem: Lenovo 8 Series HD Audio Controller
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 58
        Region 0: Memory at f0534000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd_hda_intel