Hi Devin, On Mon, Mar 23, 2015 at 8:16 PM, Devin Heitmueller <dheitmueller@xxxxxxxxxxxxxx> wrote: > Hi Alistair, > >> There are some small differences in packet ordering, however the first >> major difference is an isochronous in packet where the Live2 returns >> "URB status: No such file or directory (-ENOENT) (-2)". >> >> Devin, I'm try to learn a bit about USB and the Live2 protocol, however I'm >> not sure how far I'll get. Are you able to offer any hints on what to do >> next? > > I'm sorry if I'm asking something already answered in your original > description of the problems - but have you confirmed the device works > properly on a system with a standard EHCI controller (as opposed to > XHCI)? > > The reason I ask is because that the cx231xx driver is pretty unstable > in general, and I'm wondering if perhaps you're just hitting some > issue completely unrelated to the recent XHCI problems (which > obviously needed to be addressed in order for you to get this far into > testing). > > If you haven't tried it yet on a standard ECHI controller because you > don't have one in your PC, it might be worth spending the $20 to buy a > PCI card with an USB 2.0 host controller on it for testing. Thanks for your follow-up. I've run the same series of tests over an EHCI controller without any problems, i.e. I can record successfully regardless of whether the Live2 is plugged in during boot or after the system has settled down. At the moment I only have access to laptops, not a desktop, so the EHCI testing was on a different machine, with the Ubuntu 3.13 kernel. If you'd like me to test on a more recent kernel, please let me know. > It's also worth mentioning that the process you're exercising isn't > just the code path for device insertion. The udev process and > PulseAudio will both try to connect to the device as soon as the > underlying device nodes appear, so it's possible there is some race > condition where the device is being accessed and registers are being > poked before initialization is complete. I cannot say for certain > this would be an issue with cx231xx, but I've definitely seen it with > other V4L2 drivers. That might also explain why you see different > behavior at boot - the driver loads early enough in the boot process > such that initialization completes before processes like udev and > pulseaudio get a chance to interact with it. Good point, although the problems occur when the device is present during boot. It works fine if it is plugged in after boot. However it does appear to be some sort of timing / race condition. Any other suggestions? Do you know if the cx23102 datasheet is available? All I've been able to find is a two page sheet with a block diagram. Thanks again, Alistair -- 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
