Bug 208269

Summary:	Polaris HDMI passthrough for TrueHD and DTS-HD does not work without snoop enabled, which leads to clipping
Product:	Drivers	Reporter:	Brady (brady.w.clark)
Component:	Video(DRI - non Intel)	Assignee:	drivers_video-dri
Status:	NEW ---
Severity:	normal	CC:	brady.w.clark
Priority:	P1
Hardware:	x86-64
OS:	Linux
Kernel Version:	Tested on 5.1.16 and 5.6.18	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	\proc\asound\card0\eld#0.3 alsa-test.sh results without snoop alsa-info.sh results without snoop alsa-info.sh results with snoop forced enabled in snd_hda_intel

Description Brady 2020-06-21 17:21:17 UTC

Motherboard: Asus P8H61-M LX3 R2.0
CPU: Celeron G1610
RAM: 4GB
GPU: Yeston RX550-4G D5 LP (POLARIS11)
Receiver: Denon x6500h

Tested in Kodi on 5.1.16 (LibreELEC 9.2.3) and on 5.6.18 (Fedora 32 with Pulseaudio disabled)

Out of the box sound is crystal clear but passthrough does not work for TrueHD and DTS-HD, receiver does not show the codec and there is no audio at all with TrueHD and DTS-HD passthrough enabled.  Other codecs (AC3, DTS) passthrough fine.

Capabilities seem to be detected correctly (contents of \proc\asound\card0\eld#0.3 attached).

If I set "options snd_hda_intel snoop=1", passthrough for all codecs works as expected, but I get horrible clipping with passthrough audio, and Kodi UI clicks repeat.

alsa-test.sh results with and without snoop enabled are attached.

To note: This hardware combination works as expected in Windows, and with an nVidia GT 1030 this setup does all HDMI passthrough correctly in LibreElec as well, although it does not, of course, allow HEVC hardware decoding in LibreELEC.

Comment 1 Brady 2020-06-21 17:22:02 UTC

Created attachment 289773 [details]
\proc\asound\card0\eld#0.3

Comment 2 Brady 2020-06-21 17:22:55 UTC

Created attachment 289775 [details]
alsa-test.sh results without snoop

Comment 3 Brady 2020-06-21 17:25:32 UTC

Created attachment 289777 [details]
alsa-info.sh results without snoop

Comment 4 Brady 2020-06-21 17:26:29 UTC

Created attachment 289779 [details]
alsa-info.sh results with snoop forced enabled in snd_hda_intel

Comment 5 Brady 2020-06-21 17:30:17 UTC

I should add (headdesk) that the driver in question is amdgpu.