Hi Alan, On Wed, Jul 10, 2013 at 2:27 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > 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. I probably should have better qualified my previous statement. Every once in a while there is an actual -EOVERFLOW condition, which will result in that one frame being a bit corrupted. Those cases do show up in the URB handler via the status field. That said though, the problem I'm debugging happens 20-30 times a second, so I'm looking for something much more prevalent than one error in a five second capture. > 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.) Will that get me any new data/context I'm not already getting with the bus analyzer? I'm not against doing a Wireshark capture if it gets me access to some internal state of the USB stack that wouldn't be available to the Beagle, but at this point I've got scripts written to parse the Beagle data so it's not clear what the benefit would be. >> > 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. Agreed. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- 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
