On Thu, 05 Oct 2017 17:10:11 +0200, Tanu Kaskinen wrote: > > On Thu, 2017-10-05 at 08:38 +0200, Takashi Iwai wrote: > > On Wed, 04 Oct 2017 21:44:00 +0200, > > Tanu Kaskinen wrote: > > > > > > PulseAudio assumes that the "front" pcm device always refers to an > > > analog device, not HDMI. While that assumption is not really valid, the > > > reality is that without that assumption PulseAudio can't know whether > > > "front" and "hdmi" refer to a different or the same device. > > > > > > The HDMI LPE driver doesn't allow audio streaming while the HDMI cable > > > is unplugged, so PulseAudio has to know when it's plugged in and when > > > it's not. If both "front" and "hdmi" devices exist, PulseAudio will > > > notice that HDMI is unplugged, but it doesn't know that "front" refers > > > to the same device, and PulseAudio will try to use the "front" device > > > with bad consequences. The kernel driver's refusal to stream any audio > > > makes PulseAudio enter an infinite loop and then the kernel kills > > > PulseAudio, because it consumes too much CPU time in a realtime thread. > > > > > > While the looping in PulseAudio could probably be fixed, that wouldn't > > > change the fact that PulseAudio thinks that there is an analog device. I > > > believe it's best to avoid having the same device as both "front" and > > > "hdmi" in alsa-lib. > > > > > > I removed also the surround configuration includes. I don't think they > > > had any effect anyway, so I wonder why they were there in the first > > > place. > > > > These definitions are there for LPCM surround channels. > > Are they supposed to do something useful? When PulseAudio probes the > surround40:0 device, opening the device fails: > > alsa-util.c: Trying surround40:0 with SND_PCM_NO_AUTO_FORMAT ... > (alsa-lib)confmisc.c: Unable to find definition 'cards.HdmiLpeAudio.pcm.surround40.0:CARD=0' > (alsa-lib)conf.c: function snd_func_refer returned error: No such file or directory > (alsa-lib)conf.c: Evaluate error: No such file or directory > (alsa-lib)pcm.c: Unknown PCM surround40:0 Hm, it might be not well tested, then :) > > The biggest problem behind the scene is that we mixed up both logical > > and physical configurations. The "front" or "surround51" belong to > > the former, while "hdmi" belongs to the latter. > > > > In the past, there was only SPDIF that has only two stereo channels, > > so the logical configuration was fixed with that. We copied that > > config for HDMI/DP, and now we hit the inconsistency more clearly... > > > > I suppose the PA issue gets fixed just by this removal? If yes, I'm > > willing to apply it, including in the next release. > > A user reported that removing the "front" definition fixes the PA > issue, together with jack detection patches for PA that haven't been > merged yet. OK, I applied the patch now. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
