Hi All, I've been having some serious packet corruption issues with a usb audio device. I've found that the input packets themselves contain bad data by copying the waveform data sent from my audio device out of the packets using usbmon and some scripts. The bad data appears to be one or two samples of old data once per packet (288 bytes) and looks like it is at the beginning of the packet. This happens on 3 recent sandy bridge motherboards, on a 2.6.33 kernel and on a 3.2.13 kernel. But, it does not happen on older motherboards I have. After some investigation, I found this errata in the Intel 6 series spec: " Incorrect Data for FS/LS USB Periodic IN Transaction Problem: The Periodic Frame list entry in DRAM for a USB FS or LS Periodic IN transaction may incorrectly get some of its data from a prior Periodic IN transaction which was initiated very late into the preceding microframe " This is outlined in greater detail on page 19 of http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/6-and-c200-chipset-specification-update.pdf. It goes on to say that this was observed with asynchronous transactions. But, could this also affect isochronous transfers too? And, how would I check for such a condition? Sorry if these are newbie questions! -Louis -- 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
