Thomas Reitmayr wrote: > Am Sonntag, den 04.01.2009, 14:46 +0100 schrieb Németh Márton: >> Hi, >> >> I am currently working on a project to test video devices (webcams, >> tuners, etc.) which using the V4L2 API ( http://v4l-test.sourceforge.net/ ). >> >> There are a lot of video devices which are connected to the computer >> via USB. If I have a device available I can run the test against it. >> Some problems are exists, for example it is not so easy to create >> an automatic test which unplugs an USB device at a certain test step and >> replugs it later. >> >> If a hardware device is not available the related software driver cannot >> be tested either. >> >> I wonder if a software "USB loopback device" driver already exists, >> similar to the "lo" device in networking. This device would show up >> as a USB hardware device when it is asked to do so from the user >> space. Then the user space "simulator" would receive all USB packets >> which would normally be sent to the USB device and the "simulator" >> could react and send USB packets in the other direction. >> >> Do you know about such a driver? If not, do you think that the USB >> subsystem has a point or an interface where this can be implemented? >> > Hi Németh, > I was doing something similar to this using USB/IP 0.1.6 - just from a > few USB log files I created a device model for hardware (a USB handset) > I do not own. However for my tests I eventually switched to a virtual > environment as my system stopped responding rather frequently. I also > experienced this problem connecting to a real device over the internet. > So this is a possible solution, but might not be the best one. > Regards, > -Thomas > > References: > USB/IP: http://sourceforge.net/projects/usbip/ > My handset models: > http://www.devbase.at/svn/view.cgi/phone-models/trunk/?root=experimental > Discussions on this list: > http://search.gmane.org/?query=usbip&group=gmane.linux.usb.general&sort=relevance As far as I can see this USB/IP project implements a VHCI (Virtual Host Controller Interface) to handle the USB packets. I have to have a closer look, but as far as I remember there is a diffcerence between the original EHCI, UHCI and OHCI. For example there could be different packet sizes when using the different Host Controllers. Do you know maybe how this is handled by VHCI? Regards, Márton Németh -- 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
