Fix bogus HDMI audio interface

[Kai-Heng Feng]

[Impact]
Bogus HDMI audio can be selected as output, without any HDMI monitor
connected.

[Fix]
Consider 0 SAD as invalid ELD - no SAD means no audio.

[Test]
With the patch applied, no bogus HDMI audio can be found in GNOME's
setting app.

[Where problems could occur]
Basically none. No SAD means no PCM - so it has never worked before.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-oem-5.14/5.14.0-1012.12 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal' to 'verification-done-focal'. If the problem still exists, change the tag 'verification-needed-focal' to 'verification-failed-focal'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-oem-5.14 - 5.14.0-1013.13

---------------
linux-oem-5.14 (5.14.0-1013.13) focal; urgency=medium

  * focal/linux-oem-5.14: 5.14.0-1013.13 -proposed tracker (LP: #1955464)

  * devices on thunderbolt dock are not recognized on adl-p platform
    (LP: #1955016)
    - SAUCE: thunderbolt: Runtime PM activate both ends of the device link
    - SAUCE: thunderbolt: Tear down existing tunnels when resuming from hibernate
    - SAUCE: thunderbolt: Runtime resume USB4 port when retimers are scanned
    - SAUCE: thunderbolt: Do not allow subtracting more NFC credits than
      configured
    - SAUCE: thunderbolt: Do not program path HopIDs for USB4 routers
    - SAUCE: thunderbolt: Add debug logging of DisplayPort resource allocation

 -- Chia-Lin Kao (AceLan) <email address hidden> Tue, 21 Dec 2021 16:59:25 +0800

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 5.15.0-17.17

---------------
linux (5.15.0-17.17) jammy; urgency=medium

  * jammy/linux: 5.15.0-17.17 -proposed tracker (LP: #1957809)

 -- Andrea Righi <email address hidden> Thu, 13 Jan 2022 17:11:21 +0100