I'm cc'ing the linux-usb@ again because the original message contained some HTML, which made it bounce from the mailing list. On Sat, Nov 14, 2009 at 17:54, Javier Kohen <jkohen@xxxxxxxxxxxxxxxxxxxxx> wrote: > I tracked a problem I'm having with my USB audio DAC down to > patch cb88a1b887bb8908f6e00ce29e893ea52b074940. > > This issue is present in kernels 2.6.30.6+, 2.6.31.* and 2.6.32-rc7. > > With this patch applied, some combinations of two programs communicating > with the DAC cause the audio to vanish. The only way to restore it seems to > be to close all applications that have the DAC's devices open. After this, > all goes back to the previous functional state, though the bug can be > reproduced again by following the same steps. > > All audio applications I have use ALSA directly. I'm not running PulseAudio, > ESD or any other kind of audio daemon. I don't have other sound cards in the > system, except for the motherboard's on-board, which is disabled from the > BIOS. Some easy ways in which I can reproduce this problem: > > 1) Start playing sound with totem/gstreamer, or sox' ALSA driver (run "play" > from the command-line). > 2) Start alsamixer. Boom, the device goes silent. > > 1) Start playing sound as above. > 2) Start winecfg once Wine has been set up to use the ALSA driver. Boom, the > device goes silent. > > 1) Start a game on Steam (under Wine). Steam itself opens the audio device > first, then when the game opens in, and the audio goes silent. > > Some things that don't cause the audio to go awry: > > 1) Sox' play + totem/gstreamer playing audio at the same time. > Note that these two open the audio device separately, according to lsof, so > there's no external multiplexing. > > 1) Starting alsamixer. > 2) Then playing sound with sox or totem/gstreamer. > > ALSA recognizes the DAC as "Burr-Brown Japan PCM2702." Currently this DAC is > connected to my computer through the USB hub in my monitor, which makes it > go through the EHCI driver. When connected directly to the motherboard the > DAC uses the OHCI driver, which doesn't exhibit this problem. However, there > is a problematic interaction between the DAC and the OHCI driver or > motherboard chipset (nVidia's CK804), which causes the audio to degrade > after a while. The degradation appears first as a background hiss, until it > turns into a "broken radio" kind of sound. If anyone would like to track > down the problem with OHCI, I'm more than willing to give further details > and assistance. My intuition tells me this is an USB issue, not ALSA's. > > If there's anything else I can do to help, do let me know. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
