#qi-hardware IRC log for Sunday, 2012-04-15

wpwrakDocScrutinizer: and with ionized, aka "normal" water ? ;-)04:48
qi-botThe build was successful: http://fidelio.qi-hardware.com/~xiangfu/build-nanonote/openwrt-xburst.minimal-20120414-0526 10:03
kyakwhitequark: ha, thanks! :)10:57
Aylalarsc: hi16:15
Aylalarsc: there's a bug on the audio driver we're tring to remove16:16
larscAyla: what kind of bug16:16
Aylafrom time to time, when the DAC is enabled, a very high, loud and cyclic noise appears16:17
Aylait 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 low16:18
Aylaif we set the software volume to 4% on alsamixer, we get a high probability to trigger the bug16:25
Aylathe jz4740_pm.pdf has some info about how to reduce the noise, but I don't know at all how the driver works :)16:26
larscAyla: 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 difference16:30
Aylasure, one second16:31
Aylalarsc: no difference16:45
mthlarsc: I think the audio bug Ayla described is actually a hardware limitation that the driver should work around but currently does not18:47
mththe hw needs a certain order of powering things up and wait times between the steps18:48
GNUtoo-desktoppop and clicks in the kernel Documentation?18:48
mthit's not really a "pop" since the noise repeats periodically18:49
mthbut I do think it's related to the power-up sequence18:49
mthit's somewhere between the digital output and the DAC switch, so it could be the DAC itself18:50
mthI hope the recommended power-up sequence from Ingenic will avoid this problem as well as power-up pops and clicks18:51
mthin 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 sequence18:51
mthanother reason to suspect the DAC is that the level of the samples being played matters for the chance of triggering this bug18:52
mthit happens maybe 1 in 10 times for low volumes, and I've never been able to trigger it for high volumes18:53
mthfor a digital part, I don't think the value of the samples should matter18:53
mthso the problem would be somewhere in the analog part18:53
mthbut it is before the hw volume step, since the artifact is modified by hw volume 18:55
mthtoggling the DAC output switch is what triggers it and also what makes it go away18:55
mthbut that toggle action also causes the driver to power down a lot of the pipeline, so it might not be the hw switch18:56
mthone time I had the artifact for only 1 cycle, but usually if it appears it goes on forever18:56
mththe cycle length varies between about 0.5 and 2 seconds18:56
mthmeaning that every time the problem is triggered, one cycle length is "picked" and will be repeated until you toggle the switch again18:57
mthbut the next time the problem occurs the cycle length can be different18:57
mththere could be a relation between the sample level and the cycle length, but I haven't found firm evidence of that18:57
larscmth: so it also happens if there is no real playback?19:51
qi-bot[commit] Werner Almesberger: m1/patches/rtems/series: fix typo in date (xx0xx -> xx-xx) (master) http://qi-hw.com/p/wernermisc/08302e519:56
qi-bot[commit] Werner Almesberger: BUILD-CHEAT-SHEET: added pinning for rtems and rtems-yaffs2 (master) http://qi-hw.com/p/wernermisc/981374b20:28
mthlarsc: I'm not sure if it happens for softvol exactly 0, but for almost-0 it does happen21:10
mththe amplitude of the artifact is unrelated to the softvol value21:11
mthwhich is part of why it is so problematic: it's extremely loud21:11
mthso if you have headphones on, it's a bad experience21:11
mthI can test with openMSX and nothing emulated running21:12
mthinteresting: if the problem occurs with non-zero softvol and you then set softvol to 0, the problem doesn't go away when toggling the switch21:17
kristianpaulfree software folks, sell usb-keys at events, what we qi call sell?21:19
kristianpaulof course there is nanonote21:19
kristianpaulbut i was asked past week for selling 3 and i had no stock here :(21:19
mthand I can't reproduce it with softvol exactly 0, only with softvol just above 021:20
kristianpaulof course i took mails from people, lets see if it still sell some at the end..21:20
mthso it seems a soft sound output is needed to trigger it: no sound or loud sound means it won't occur21:21
mthI've got the high-pitch part at a ~10 sec cycle now21:21
mthit's like a siren that starts at a medium-high pitch and then goes up into unhearable range21:22
whitequarkkyak: no idea what you were talking about, but YW21:22
mthcombined with a noisy garbled sound that is less loud21:22
mththis is what it sounds like: http://www.treewalker.org/temp/audio_problem.ogg21:49
mththis is with the very slow cycle, usually the high-pitch sound envelopes much faster and the cycle is 0.5-2 sec21:49
mthit's not so loud in this recording, but it was recorded from the speakers; from the headphones it's really loud21:50
virickristianpaul: people want to give Qi money to fund the project, but wants some object for the money?21:57
virickristianpaul: this is silly.21:58
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