On Wed, 10 Jul 2013, Devin Heitmueller wrote: > > I don't see any problems in the usbmon trace, but they might not show > > up there. In particular, the trace includes the status values only for > > the first 5 packets in each URB. Does the driver encounter any packets > > with a nonzero status? > > No. I added code to the driver to do a printk() on any error > conditions (both at the URB level and at the isoc packet level), and > the log has been clean. You inspired me to take a closer look at the usbmon log you made available. There _is_ an error indication after all; the line with timestamp 397263317 got an error in one of its 64 packets (but this was the only error in the entire trace). The trace doesn't say what the error was or which packet it occurred in. This error should have shown up in your driver as a nonzero value for the packet status. If you want to investigate further, you can capture the entire data stream using Wireshark. (Of course, that means capturing 22 MB/s of data.) > > It could be that you're facing some sort of hardware limitation of the > > host controller. Can you try running the test on a computer with a > > different brand of motherboard? > > Ruled that out already. I'm seeing the behavior on my 2010 MacBook > Pro (Intel EHCI), a Dell XPS system (also Intel EHCI), and a TI 8147 > Davinci embedded system (using the musb HCD), I've also tried three > different Empia designs and they all exhibit the same behavior > (em2820, em2861, em2883). It's hard to see how they could all suffer from the same hardware bug. Alan Stern -- 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
