On Tue, Jan 06, 2009 at 07:30:27AM +0100, Németh Márton wrote: > 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? The code is in the 2.6.28 kernel tree in drivers/staging/usbip/ for you to poke around with if you want to. good luck, greg k-h -- 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
