Topic for #qi-hardware is now Copyleft hardware - http://qi-hardware.com | hardware hackers join here to discuss Ben NanoNote, atben / atusb 802.15.4 wireless, and other community driven hw projects | public logging at http://en.qi-hardware.com/irclogs
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<wpwrak> DocScrutinizer: and with ionized, aka "normal" water ? ;-)
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<DocScrutinizer> depends
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<kyak> whitequark: ha, thanks! :)
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<Ayla> larsc: hi
<Ayla> larsc: there's a bug on the audio driver we're tring to remove
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<larsc> Ayla: what kind of bug
<Ayla> from time to time, when the DAC is enabled, a very high, loud and cyclic noise appears
<Ayla> it is very easy to make it appear on OpenDingux, as it seems to occur more easily when the sound submitted by the ALSA userspace library is very low
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<Ayla> if we set the software volume to 4% on alsamixer, we get a high probability to trigger the bug
<Ayla> the jz4740_pm.pdf has some info about how to reduce the noise, but I don't know at all how the driver works :)
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<larsc> Ayla: can you try to swap the cpu_dai and platform section in soc_pcm_open in soc-pcm.c and see if it makes any difference
<Ayla> sure, one second
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<Ayla> larsc: no difference
<larsc> ok
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<mth> larsc: I think the audio bug Ayla described is actually a hardware limitation that the driver should work around but currently does not
<mth> the hw needs a certain order of powering things up and wait times between the steps
<GNUtoo-desktop> pop and clicks in the kernel Documentation?
<mth> it's not really a "pop" since the noise repeats periodically
<mth> but I do think it's related to the power-up sequence
<GNUtoo-desktop> ok
<mth> it's somewhere between the digital output and the DAC switch, so it could be the DAC itself
<mth> I hope the recommended power-up sequence from Ingenic will avoid this problem as well as power-up pops and clicks
<mth> in any case, I don't think this issue was ever reported with the Ingenic kernel and that audio driver has a very elaborate power-up sequence
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<mth> another reason to suspect the DAC is that the level of the samples being played matters for the chance of triggering this bug
<mth> it happens maybe 1 in 10 times for low volumes, and I've never been able to trigger it for high volumes
<mth> for a digital part, I don't think the value of the samples should matter
<mth> so the problem would be somewhere in the analog part
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<mth> but it is before the hw volume step, since the artifact is modified by hw volume
<mth> toggling the DAC output switch is what triggers it and also what makes it go away
<mth> but that toggle action also causes the driver to power down a lot of the pipeline, so it might not be the hw switch
<mth> one time I had the artifact for only 1 cycle, but usually if it appears it goes on forever
<mth> the cycle length varies between about 0.5 and 2 seconds
<mth> meaning that every time the problem is triggered, one cycle length is "picked" and will be repeated until you toggle the switch again
<mth> but the next time the problem occurs the cycle length can be different
<mth> there could be a relation between the sample level and the cycle length, but I haven't found firm evidence of that
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<larsc> mth: so it also happens if there is no real playback?
<qi-bot> [commit] Werner Almesberger: m1/patches/rtems/series: fix typo in date (xx0xx -> xx-xx) (master) http://qi-hw.com/p/wernermisc/08302e5
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<qi-bot> [commit] Werner Almesberger: BUILD-CHEAT-SHEET: added pinning for rtems and rtems-yaffs2 (master) http://qi-hw.com/p/wernermisc/981374b
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<mth> larsc: I'm not sure if it happens for softvol exactly 0, but for almost-0 it does happen
<mth> the amplitude of the artifact is unrelated to the softvol value
<mth> which is part of why it is so problematic: it's extremely loud
<mth> so if you have headphones on, it's a bad experience
<mth> I can test with openMSX and nothing emulated running
<mth> interesting: if the problem occurs with non-zero softvol and you then set softvol to 0, the problem doesn't go away when toggling the switch
<kristianpaul> free software folks, sell usb-keys at events, what we qi call sell?
<kristianpaul> of course there is nanonote
<kristianpaul> but i was asked past week for selling 3 and i had no stock here :(
<mth> and I can't reproduce it with softvol exactly 0, only with softvol just above 0
<kristianpaul> of course i took mails from people, lets see if it still sell some at the end..
<mth> so it seems a soft sound output is needed to trigger it: no sound or loud sound means it won't occur
<mth> I've got the high-pitch part at a ~10 sec cycle now
<mth> it's like a siren that starts at a medium-high pitch and then goes up into unhearable range
<whitequark> kyak: no idea what you were talking about, but YW
<mth> combined with a noisy garbled sound that is less loud
<mth> this is what it sounds like: http://www.treewalker.org/temp/audio_problem.ogg
<mth> this is with the very slow cycle, usually the high-pitch sound envelopes much faster and the cycle is 0.5-2 sec
<mth> it's not so loud in this recording, but it was recorded from the speakers; from the headphones it's really loud
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<viric> kristianpaul: people want to give Qi money to fund the project, but wants some object for the money?
<viric> s/wants/want
<qi-bot> viric meant: "kristianpaul: people want to give Qi money to fund the project, but want some object for the money?"
<viric> kristianpaul: this is silly.
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