vc4.ko brings unusable&unstable ALSA sinks

[Ryutaroh Matsumoto]

Hi, This is an updates on pulseaudio on RPi:

On my RPi4 with module_blacklist=snd_bcm, I have the following multi-channel
capable output:

$ LANG=C.UTF-8 pacmd list-cards
1 card(s) available.
    index: 0
	name: <alsa_card.platform-fef00700.hdmi>
	driver: <module-alsa-card.c>
	owner module: 6
	properties:
		alsa.card = "0"
		alsa.card_name = "vc4-hdmi-0"
		alsa.long_card_name = "vc4-hdmi-0"
		alsa.driver_name = "vc4"
		device.bus_path = "platform-fef00700.hdmi"
		sysfs.path = "/devices/platform/soc/fef00700.hdmi/sound/card0"
		device.form_factor = "internal"
		device.string = "0"
		device.description = "Built-in Audio"
		module-udev-detect.discovered = "1"
		device.icon_name = "audio-card"
	profiles:
		output:iec958-stereo: Digital Stereo (IEC958) Output (priority 5500, available: unknown)
		output:iec958-ac3-surround-51: Digital Surround 5.1 (IEC958/AC3) Output (priority 300, available: unknown)
		off: Off (priority 0, available: unknown)
	active profile: <output:iec958-stereo>
	sinks:
		alsa_output.platform-fef00700.hdmi.iec958-stereo/#0: Built-in Audio Digital Stereo (IEC958)
	sources:
		alsa_output.platform-fef00700.hdmi.iec958-stereo.monitor/#0: Monitor of Built-in Audio Digital Stereo (IEC958)
	ports:
		iec958-stereo-output: Digital Output (S/PDIF) (priority 0, latency offset 0 usec, available: unknown)
			properties:

In the above "active profile: <output:iec958-stereo>" indicates the
default is not multichannel. I believe that the default can be changed to
the multichannel by (from pulse-cli-syntax(5)):

       set-card-profile index|name profile-name
              Change the profile of a card.
       set-sink-port|set-source-port index|name port-name
              Change the profile of a sink (resp. source).

Best regards, Ryutaroh