Open-Source AMD Polaris Audio Support Isn't Coming Until DAL Lands

[Krejzi]

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde XT [Radeon HD 7770/8760 / R7 250X]
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series]

That's still SI (GCN 1.0). It uses radeon kernel driver, not amdgpu. This article is about amdgpu kernel driver.

[droste]

Interesting, you guys say that it never stopped working for you? I have a Marantz NR1504 on HDMI without a monitor, main monitor is a 4K screen connected via DP. But even tried two different Fake-HDMI-EDID-sticks on the receiver, no luck anymore on Linux. Deucher confirmed me in May that in needs DAL. No audio at all so far, 5.1 as well as stereo. With my older HD 7770 on 3.19 and upwards, PulseAudio showed for HDMI only "unplugged" options, sometimes, after several reboots into Window, sound worked with heavy stuttering but a couple kernels later even that stopped and there was no way to get any sound over HDMI. My newer R9 380 just shows the HDMI options (Stereo, 5.1, 7.1), now without "unplugged" in pavucontrol, it still doesn't do any output.

With the radeon kernel driver it always worked/is working for me. I have a r9 270 connected via HDMI to an AV receiver and never had any problems (5.1 is working fine).

[tomtomme]

Actually, this is broken on radeonsi since at least Linux 3.19. YES, 3.18 was the last kernel which got me working HDMI audio (Radeon HD 7770, later R9 380 with AMDGPU, same problem). It is super, ultra 'annoying'. Months before the problems started, I just bought a new HDMI receiver for my expensive 5.1 PC setup. I'm using S/PDIF ever since, which only supports lossless stereo. Have to reboot to Windows to use the damn 5.1 setup. This situation is even worse considering that my whole movie archive is on Linux partitions on XFS and btrfs for which there aren't any Windows drivers. In my desperation I even installed a second distribution using the proprietary Catalyst driver – couldn't use Catalyst because of the problems with Firefox' OMTC which I don't want to miss and various other desktop issues, radeon(si) was much better. Don't wanted to buy any Nvidia hardware, but seriously AMD, this audio situation for at last 1,5 years with the free drivers is outrageous disappointing!

There is a btrfs win driver, there was a phoronix story about it some days ago.
And there is 5.1 spdif support at least in kodi. But i think it also generally works with pulse audio. Just set spdif stereo and mark dts etc then 5.1 will be passed through.

I also wait for gpu audio, in my case for fiji. I think all amdgpu using cards are missing it. But you can go amdgpu-pro to get it today.

[holunder]

@TomTomme: The highly experimental btrfs driver for Windows requires compilation and Windows booted into safe mode, besides it seems it is rw by default and it would be great idiocy to let it go on my unmirrowed data…
Yes, S/PDIF supports 5.1, of course, but only for DD/DTS signals. I mostly have ripped Blu-rays with lossless tracks converted to FLAC → de facto PCM signal that requires a way greater bandwidth than S/PDIF provides. But thanks for your suggestions anyway.
Just tried installing amdgpu-pro from AUR but I'm using Manjaro and the AUR packages do conflict with too many required system packages…

[starshipeleven]

Actually, this is broken on radeonsi since at least Linux 3.19. YES, 3.18 was the last kernel which got me working HDMI audio (Radeon HD 7770, later R9 380 with AMDGPU, same problem).

Did you try disabling integrated audio? I've had plenty of issues with soundcards and HDMI audio that magically went away if I disabled the integrated audio from UEFI.

[starshipeleven]

I'm not sure what the problem with HDMI audio on video cards is. I mean, it's just digital signal that needs to pass through. That's all. There's no decoding/transcoding involved, no DACs, no ADCs... I'm probably missing something obvious (again), but it just doesn't add up in my head.

Technically speaking, digital sound streams still need to be assembled with video stream as the protocol used to move struff through HDMI cable is TMDS, and both audio and video are together.

https://www.epiphan.com/blog/hdmi-audio-over-dvi-how-does-that-work/

So whatever allows sound to pass through HDMI needs to alter the code in the driver that deals with sending video through HDMI, it's not using dedicated lines for audio, that would have been easy.

That is where what I know ends.

[starshipeleven]

I'm not sure what the problem with HDMI audio on video cards is. I mean, it's just digital signal that needs to pass through. That's all. There's no decoding/transcoding involved, no DACs, no ADCs... I'm probably missing something obvious (again), but it just doesn't add up in my head.

AFAIK HDMI sends both audio and video through the same pins using the same protocol (TMDS), so whatever adds the audio to the HDMI stream is also very connected to crucial parts of the driver.
This means you can (among other things) sniff full HDMI output from DVI ports too (that shouldn't carry audio) as long as the source is on HDMI.

https://www.epiphan.com/blog/hdmi-audio-over-dvi-how-does-that-work/

If audio was running on separated lines using its own protocol it would have been a whole lot easier.

[starshipeleven]

I'm not sure what the problem with HDMI audio on video cards is. I mean, it's just digital signal that needs to pass through. That's all. There's no decoding/transcoding involved, no DACs, no ADCs... I'm probably missing something obvious (again), but it just doesn't add up in my head.

AFAIK HDMI sends both audio and video through the same pins using the same protocol (TMDS), so whatever adds the audio to the HDMI stream is also very connected to crucial parts of the driver.
This means you can (among other things) sniff full HDMI output from DVI ports too (that shouldn't carry audio) as long as the source is on HDMI.

https://www.epiphan.com/blog/hdmi-audio-over-dvi-how-does-that-work/

If audio was running on separated lines using its own protocol it would have been a whole lot easier.

[starshipeleven]

@bug77: AFAIK HDMI sends both audio and video through the same pins using the same protocol (TMDS), so whatever adds the audio to the HDMI stream is also very connected to crucial parts of the driver.
This means you can (among other things) sniff full HDMI output from DVI ports too (that shouldn't carry audio) as long as the source is on HDMI.

https://www.epiphan.com/blog/hdmi-audio-over-dvi-how-does-that-work/

If audio was running on separated lines using its own protocol it would have been a whole lot easier.

[starshipeleven]

this unapproved post feature is starting to be annoying.

@bug77: AFAIK HDMI sends both audio and video through the same pins using the same protocol (TMDS), so whatever adds the audio to the HDMI stream is also very connected to crucial parts of the driver.
This means you can (among other things) sniff full HDMI output from DVI ports too (that shouldn't carry audio) as long as the source is on HDMI.

https://www.epiphan.com/blog/hdmi-audio-over-dvi-how-does-that-work/

If audio was running on separated lines using its own protocol it would have been a whole lot easier.