2014-03-20 10:52 GMT+01:00 Peter Stuge <peter@xxxxxxxx>: > I understand the expectation, but I don't think Linux meets it. > > The difference in your logs is the usbX bus number, which really can > not persist beyond the lifetime of that bus. > > Think of a laptop with a CardBus slot. CardBus is just PCI. If you > plug a USB host card into that laptop, which number will the new usbX > bus have? > > What if that same card is plugged in during boot? > > What if the card is unplugged? The usbX goes away. And then the card > is plugged back in. A new usbX comes in. X is only valid for the > lifetime of that bus. For soldered-on buses like in the chipset this > means until reboot. OK. I don't fully understand the details, but I think I got your point. > I think your best chance is to filter out the usbX bus name yourself. > > E.g. match on the DEVPATH prefix /devices/pci0000:00/0000:00:1d.7/ > and on the suffix -4.1:1.0/usbmisc/pcanusb* That seems good enough to make an udev rule, I will try ASAP. :-) > That will always match the same pcanusb device plugged into the same > physical port, as long as chipset or firmware (BIOS upgrade) does not > remap PCI devices and/or device functions. While hardware might > support such remapping, in particular if the hardware is virtualized, > as is increasingly the case, devfns changing is rare. But you do need > to coordinate this with whoever is your BIOS engineer if you want > actual reliability. Ok, we will have that into account. I think it will be acceptable with our little knowledge on the issue. Thank you very much! We've struggled quite a bit with this. -- Alejandro Exojo Piqueras ModpoW, S.L. Technova LaSalle | Sant Joan de la Salle 42 | 08022 Barcelona | www.modpow.es -- 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
