On 18 March 2010 22:06, Pedro Ribeiro <pedrib@xxxxxxxxx> wrote: > Hi all, > > I've been having a problem lately with two of my USB devices. > > I have a DVB-T USB adapter (to watch tv on my laptop) and a Native > Instruments Audio4DJ USB sound card. > > Both devices work wonderfully when I come from a fresh boot (I can > watch tv with the audio routed through the sound card). However, once > I disconnected the audio card and reconnect again, I get this regular > but not periodic interference on the audio card. > By "regular and not periodic" I mean that the time elapsed between > each interference is random, from 0.5 to 30 seconds, but it keeps > happening. The interference is a kind of crack and pop which affects > all output channels of the audio card. > > From now on (until I fresh boot again), I can reconnect the audio card > as many times as I want, rmmod and modprobe its module again and I > always get the interference. Note that unplugging and plugging the DVB > adapter makes no difference, and if I fresh boot, connect both > devices, disconnect the DVB card and reconnect, I do not get > interference - only when I do the same with the audio card. > > After much research I found the culprit - apparently if I rmmod and > modprobe the ehci_usb device the interference is gone without having > to fresh boot (of course before this I unload the modules for the dvb > and audio devices). > > I was to able to reproduce this problem in kernels 2.6.31 to 2.6.33 (I > haven't tried any others). I WAS NOT able to reproduce on a ICH4 > laptop I have. > > The DVB-T adapter uses the dvb_usb_dib0700 module and the audio card > uses the snd-usb-caiaq module. > > My laptop is a Lenovo T400. > > Attached are the lsusb and lspci -vvv. Please let me know if you need > any more information. > > I'm mailing here for advice before I file a kernel bug, if you can > help me anyway I would appreciate it very much. > > Thanks, > Pedro > I have filed a kernel bug at https://bugzilla.kernel.org/show_bug.cgi?id=15580 Not sure if I filed on the right place - this might be specific to my platform as I wasn't able to reproduce in one other ICH4-based laptop. But then again only one other platform is not enough for a conclusion. Regards, Pedro -- 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
