Hi all, we are considering removing the backup-PCM logic from snd_hda_intel HDMI/DP audio driver (note: this is used for wide variety of HDA controllers, not just Intel ones). See mail thread on alsa-devel: https://mailman.alsa-project.org/pipermail/alsa-devel/2019-August/154561.html In short, with DisplayPort-MST, additional monitors connected to a MST hub, and/or to monitor upstream DP ports, these would be routed to separate ALSA PCMs, e.g. PCM9 and PCM10, leaving the "standard" PCM numbers free for non-MST monitors. This is getting highly problematic, especially when we support HDMI audio with systems that have a DSP, and the PCM<->HDMI-audio-converter mapping can be essentially arbitrary. The proposal is to just expose N pieces of PCMs (N number of converters in hw, e.g. 3 with i915), and any connected monitor (MST or not), is roured to one these PCMs. Tanu added the ELD autodetect support in PA-12.x, and after that, HDA + PA works pretty nicely even without the backup PCMs, and a non-standard PCM device numbering for HDMI audio. Now, I'm writing here as some kernel devs have referred to Pulseaudio as the source for the requirement to map MST monitors to the backup/virtual PCMs. Can anyone of you recall what was this about? _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
