Bug 80162

Summary: center and lfe channels screwed up on suspend
Product: DRI Reporter: Pierre Ossman <pierre-bugzilla>
Component: DRM/RadeonAssignee: Default DRI bug account <dri-devel>
Status: RESOLVED NOTOURBUG QA Contact:
Severity: normal    
Priority: medium    
Version: unspecified   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:

Description Pierre Ossman 2014-06-17 20:09:11 UTC 
Started out in the kernel bugzilla as I figured this was an alsa driver problem:

https://bugzilla.kernel.org/show_bug.cgi?id=77901

> AMD HDMI audio output. Works fine until I suspend the machine. After resume, center channel is silent and LFE channel is sent as center.
> 
> Massive issue as the center channel is the most used one of all in multichannel audio sources. :/
> 
> Unloading just snd_hda_intel and reloading it seems to work around the issue.

The verdict there though was that it didn't seem like the audio end was doing anything wrong, so it must be something in the graphics driver.

Help?
Comment 1 Alex Deucher 2014-06-17 21:10:35 UTC 
AFAIK, video driver doesn't have anything to do with the mappings.  Does forcing a modeset after resume help?  E.g., change the mode with xrandr and see if that helps.  Maybe some of the AMD specific verbs in the hda driver need to be reset?

http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/10/AMD_HDA_verbs_v2.pdf
Comment 2 Pierre Ossman 2014-06-18 19:42:55 UTC 
Thanks. Going through the vendor verbs revealed the issue. Multichannel mode was getting reset on suspend, and was not properly reinitialised by the driver on resume.

Will prepare a patch for the ALSA folks. I guess you can close this bug entry as invalid.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.