On Sun, Oct 03, 2021 at 11:00:15AM +0400, Christian Hewitt wrote: > > > On 3 Oct 2021, at 9:13 am, Geraldo Nascimento <geraldogabriel@xxxxxxxxx> wrote: > > > > On Sun, Oct 03, 2021 at 01:43:12AM +0200, Martin Blumenstingl wrote: > >> Hello Jerome et al., > >> > >> on Amlogic Meson SoCs which use the AIU audio controller we have the > >> so-called "machine gun noise" (MGN) issue, reproducible for example in > >> Kodi. So far nobody was able to identify the cause of this issue. My > >> idea was to at least narrow down the issue so we can categorize it. For > >> that I wanted to get the SPDIF output from AIU to the HDMI controller > >> working. > >> > > > > Hi, Martin, > > > > The MGN issue surely must be that one when using ALSA directly > > (no dmix, no JACK, no Pulseaudio, no Pipewire, no nothing) and > > when the track changes or we pause it, when it resumes we get > > noise instead of sound, correct? > > > > If so, thanks for trying to track this down! > > > > I bring it up because Googling it seems to head straight to a > > Neil Armstrong post to linux-amlogic about what works and what > > doesn't on linux-meson currently, and only if you dig deeper > > you find a couple of reports apparently by the same person > > about the "machine gun noise" thing. > > > > It doesn't sound like a machine gun noise to me :) > > > > More like brown noise, but anyway what I'd like to note to > > everyone involved is that this one is a major dealbreaker. > > Unless using JACK, Pulseaudio, Pipewire (?) or at least dmix > > audio will degrade at the second song or when the user first > > pauses and then resumes a stream, completely ruining the > > experience. > > > I’m the origin of most reports that Google will eventually > discover. I was told elsewhere that this is known as MGN so > I’ve described it as such, but that could be wrong. For > clarity this is the noise (triggered, and with AVR volume > deliberately right down) followed by some navigation in the > Kodi GUI to change output: > > https://chewitt.libreelec.tv/testing/wp2_audio_noise.mov > Hi, Christian, Thanks for the video. > In the LibreELEC images I work on where this occurs it’s not > something I associate with play/pause (although I can’t > definitively rule it out) or second or third songs > (not something that happens that often or predictably) but > more when there’s a hard transition like starting or > stopping playback. I hit it most with simple scrolling around > in the Kodi GUI, although that could be because (due to this issue) > I limit media playback testing on AIU devices. It’s particularly > simple to trigger from the Kodi Settings > System > Audio page, > just scroll around it for 10-30 seconds, which is handy because > the only way to stop the noise is switching audio source (from > anything to anything) on the same page. > > CH. > I wasn't able to reproduce the bug by simply scrolling around. On the other hand, once I flipped the Send Low Volume Noise switch to off, all hell broke loose! This is one show-stopper bug, and I empathize to how particularly nasty this must be for a "Just enough Linux for Kodi" approach. But I also see Jerome Brunet has already clarified the subject in response to Martin Blumenstingl's original post. Thank you, Geraldo Nascimento > >> On Amlogic Meson GXBB/GXL/GXM SoCs a DesignWare HDMI TX controller is > >> used. This has an SPDIF input but there's currently not driver for it. > >> On Meson8/8b/8m2 SoCs I am working on a HDMI driver for the TransSwitch > >> HDMI controller which - just like DesignWare HDMI TX - supports SPDIF > >> and I2S inputs. > >> I decided to add SPDIF support to the latter since the code from the > >> vendor driver is much easier. > >> > >> It took me a while to figure out why I would not get any audio output > >> from AIU SPDIF to the HDMI controller - or from there to the sink. > >> The "fix" for this issue is the RFC patch which is part of this series. > >> Any feedback would be great as I am still new to the ASoC subsystem. > >> > >> Another part I am still struggling with is the audio "routing" (due to > >> lack of a better term - please correct me if this is not the right word > >> to use for this case). I have the following description in my .dts: > >> sound { > >> compatible = "amlogic,gx-sound-card"; > >> model = "M8B-ODROID-C1"; > >> > >> assigned-clocks = <&clkc CLKID_MPLL0>, > >> <&clkc CLKID_MPLL1>; > >> assigned-clock-rates = <294912000>, > >> <270950400>; > >> dai-link-0 { > >> sound-dai = <&aiu AIU_CPU CPU_I2S_FIFO>; > >> }; > >> > >> dai-link-1 { > >> sound-dai = <&aiu AIU_CPU CPU_SPDIF_FIFO>; > >> }; > >> > >> dai-link-2 { > >> sound-dai = <&aiu AIU_CPU CPU_I2S_ENCODER>; > >> dai-format = "i2s"; > >> mclk-fs = <256>; > >> > >> codec-0 { > >> sound-dai = <&aiu AIU_HDMI CTRL_I2S>; > >> }; > >> }; > >> > >> dai-link-3 { > >> sound-dai = <&aiu AIU_CPU CPU_SPDIF_ENCODER>; > >> > >> codec-0 { > >> sound-dai = <&aiu AIU_HDMI CTRL_PCM>; > >> }; > >> }; > >> > >> dai-link-4 { > >> sound-dai = <&aiu AIU_HDMI CTRL_OUT>; > >> > >> codec-0 { > >> sound-dai = <&hdmi_tx>; > >> }; > >> }; > >> }; > >> The driver for &hdmi_tx defines: > >> struct hdmi_codec_pdata pdata = { > >> .ops = &txc_48352_hdmi_codec_ops, > >> .i2s = 1, > >> .spdif = 1, > >> .max_i2s_channels = 8, > >> .data = priv, > >> }; > >> In hdmi_codec_ops.hw_params I always get fmt->fmt HDMI_I2S unless I > >> remove all I2S references from the .dts snipped above (only then > >> HDMI_SPDIF is detected). Based on the selection of the "HDMI Source" > >> enum in aiu-codec-ctrl I was expecting the format to update as well. > >> That unfortunately doesn't happen and I don't know how that can be > >> achieved. > >> > > > > Hm, that sounds weird. I hope you get the answers you are looking for. > > > > Thanks, > > Geraldo Nascimento > > > >> > >> Best regards, > >> Martin > >> > >> > >> Martin Blumenstingl (1): > >> ASoC: meson: aiu: Fix HDMI codec control selection > >> > >> sound/soc/meson/aiu-codec-ctrl.c | 108 ++++++++++++++++++++++-------- > >> sound/soc/meson/aiu-encoder-i2s.c | 6 -- > >> 2 files changed, 80 insertions(+), 34 deletions(-) > >> > >> -- > >> 2.33.0 > >> > > >
