https://bugzilla.kernel.org/show_bug.cgi?id=86351
Bug ID: 86351 Summary: HDMI audio garbled output on Radeon R9 280X Product: Drivers Version: 2.5 Kernel Version: 3.17 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Video(DRI - non Intel) Assignee: drivers_video-dri@kernel-bugs.osdl.org Reporter: joker@netswarm.net Regression: No
Created attachment 153891 --> https://bugzilla.kernel.org/attachment.cgi?id=153891&action=edit dmesg output
Any sound played back over HDMI results in garbled audio output.
When playing audio at 24000hz or below (19200Hz also tested) playback starts to work normaly without the constant choppyness.
What also works is 44100Hz in Mono.
It behaves like a data bandwith issue that kicks in above 24000hz Stereo or 44100Hz Mono.
All test are done directly talking to the alsa device. This means no pulseaudio or dmix or similar processing. "plughw" had to be used because the hardware does not allow low rates like 24000.
During all Test a perfectly fine and stable 1080p image is displayed over HDMI. (No dropouts at all).
This hardware setup has also be successfully tested using Windows. (Incl. Multi channel PCM 6.0 for lot's of audio bandwidth)
Working Audio Tests: -------------------- speaker-test -r 24000 -c2 speaker-test -r 24000 -c6 (multi channel PCM works too)
mpg123 -r 24000 <file> mpg123 -m -r 44100 <file>
The peer format detection is pcm 2.0 44100 or 48000 here. It appears the format link doesn't matter, only the actual data bandwidth that's being used)
Garbled Audio Tests: -------------------- speaker-test -r 48000 -c2 speaker-test -r 48000 -c6
mpg123 -r 44100 <file>
All passthru formats (dts, dolby d, pcm multi channel) get detected my the destination, but after a short period it loses the link and tries to resync.
What previously also worked is a HD5570 in the same system which i no longer have access to though. Not sure about the kernel used back then.