On 24 March 2010 15:37, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 23 Mar 2010, Pedro Ribeiro wrote: > >> Just to clear things up (hopefully) the behaviour described above is >> only for the first time, when I boot the system. Once I load the >> modules in the order specified above, I always get the interference >> even if I unload them all and reload them NOT in that order - what I >> mean is once the damage is done, its irreversible - I can't use both >> at the same time. > > This is very puzzling, and I don't see any reason for the behavior > you're describing. The only thing I can think of is that somehow the > audio card gets into a bad state which persists until it is reset. > > You can test this by using the attached usbreset program. Start by > triggering the interference, and then stop using both cards (don't > stream any TV and don't stream any audio). In fact, to be safe, you > should unload both drivers. > > While the cards are idle, use the program to reset the audio card > (you'll have to run it as root). You just tell it the name of the USB > device to reset. For example, according to your dmesg log the audio > card was device 3 on bus 1, so you would do: > > sudo ./usbreset /dev/bus/usb/001/003 > > Then reload the audio driver, try streaming some normal ALSA audio, > and see if the interference has gone away. > > Alan Stern > Hi Alan, It is with great pleasure to announce that I have made some progress. One thing I'm 100% sure now is that this bug ONLY occurs with 64 bit kernel and userland. With a i686 kernel/userland, there is no interference. This is always reproducible. I downloaded Ubuntu 10.04 Beta 1 live CD's for i386 and amd64 and decided to try them out. With the amd64 one I get the interference, with the i386 I do not! I tested with another platform (a friend's laptop) and I can reproduce the results: with amd64 I get the interference, with i386 nothing. His chipset is also ICH9. Unfortunately I don't have any other platform where I can test it. Please let me know if you need the lspci and lsusb for his platform. So does this ring a bell? I had no idea there was a difference in USB handling in the kernel between 32 and 64 bit! Regards, Pedro http://bugzilla.kernel.org/show_bug.cgi?id=15580 -- 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
