On Wed, 22 Jul 2009, Manuel Lauss wrote: > > This clearly is not working right, but I can't tell exactly what's > > wrong. Can you repeat the test, this time acquiring a usbmon trace > > starting before the test and ending after the rmmod? You'll have to > > use usbmon's 0u file, so try to minimize any other USB activity going > > on at the same time. > > I can't reproduce it if I do a trace after ehci-hcd has been inserted; i.e. the > busy dma-pool only happens if I don't capture any usbmon output after > insertion and before removal of ehci-hcd. So whatever it is, it must be timing-related. > I uploaded a trace here [1], it starts with loading of ehci-hcd, then ~5 seconds > pause, read some data from ACM device, again some pause then unload > of ehci-hcd. Still not clear, but I'm getting some ideas. Let's try another approach. For this to work you'll have to enable CONFIG_USB_DEBUG as well as CONFIG_DEBUG_FS. Run your test again, without usbmon. But before removing ehci-hcd, mount a debugfs filesystem and look in the usb/ehci/au1xxx-ehci.0 directory. There should be a bunch of files with names like "registers", "async", and "periodic"; let's see what they contain. > > As for why the device doesn't work when you reload ehci-hcd, I have no > > idea. That's a separate matter and we can deal with it later. Maybe > > fixing the first problem will also fix the second. > > doing insmod ehci-hcd ; rmmod ehci-hcd; insmod ehci-hcd is enough > to render the device silent; however rmmod cdc-acm ; modprobe cdc-acm > is fine. Still, opening the device generates hcd interrupts. Maybe comparing usbmon traces of the first and second insmods will show something. 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
