Am Thu, 22 Jan 2009 16:57:36 +0100 schrieb Laurent Pinchart <laurent.pinchart@xxxxxxxxx>: > On Thursday 22 January 2009, Carsten Meier wrote: > > Am Thu, 22 Jan 2009 00:20:00 +0100 > > > > schrieb Laurent Pinchart <laurent.pinchart@xxxxxxxxx>: > > > Hi Carsten, > > > > > > On Wednesday 21 January 2009, Carsten Meier wrote: > > > > now I want to translate bus_info into a sysfs-path to obtain > > > > device-info like serial numbers. Given a device reports > > > > "usb-0000:00:1d.2-2" as bus_info, then the device-info is > > > > located under "/sys/bus/usb/devices/2-2", which is a symlink to > > > > the appropriate /sys/devices/ directory, right? > > > > > > I'm afraid not. In the above bus_info value, 0000:00:1d.2 is the > > > PCI bus path of your USB controller, and the last digit after the > > > dash is the USB device path. > > > > > > > All I have to do is to compare the first 4 chars of bus_info > > > > against "usb-", get the chars after "." and append it to > > > > "/sys/bus/usb/devices/" to obatin a sysfs-path, right? > > > > > > > > Is there a more elegant solution or already a function for > > > > this? Can the "." appear more than once before the last one? > > > > > > Probably not before, but definitely after. > > > > > > Root hubs get a USB device path set to '0'. Every other device is > > > numbered according to the hub port number it is connected to. If > > > you have an external hub connected on port 2 of your root hub, > > > and have a webcam connected to port 3 of the external hub, > > > usb_make_path() will return "usb-0000:00:1d.2-2.3". > > > > > > Cheers, > > > > > > Laurent Pinchart > > > > Hi, > > > > On my machine, my pvrusb2 (connected directly to my mini-pc) shows > > up under "/sys/bus/usb/devices/7-2/" which is a symbolic link to > > "../../../devices/pci0000:00/0000:00:1d.7/usb7/7-2" > > You're just lucky that USB bus 7 (usb7/7) is connected to the 7th > function of your USB host controller (1d.7). > > Here's an example of what I get on my computer: > > /sys/bus/usb/devices/4-2 > -> ../../../devices/pci0000:00/0000:00:1d.2/usb4/4-2 > > > I can't test for the new bus_info-string, because it's not fixed > > yet in the driver. But if I got it correctly it should be > > "usb-0000:00:1d.7-7.2" ? > > I think you will get usb-0000:00:1d.7-2 > > > Then I've to simply take the string after the last dash, replace > > "." by "-" and append it to "/sys/bus/usb/devices/" for a > > sysfs-path? > > Unfortunately the mapping is not that direct. The part before the > last dash identifies the USB host controller. The part after the last > dash identifies the device path related to the controller, expressed > as a combination of port numbers. > > The sysfs device path /sys/bus/usb/devices/7-2/ includes a USB bus > number (in this case 7) that is not present in usb_make_path()'s > output. > > To find the sysfs path of your USB peripheral, you will have to find > out which bus number the bus name (0000:00:1d.7) corresponds to. You > might be able to find that by checking each usb[0-9]+ links > in /sys/bus/usb/devices and comparing the link's target with the bus > name. > > Best regards, > > Laurent Pinchart Hi, I'll scan the link-targets of /sys/bus/usb/devices/usb[0-9] and compare them against the bus name. Now I've the problem of extracting the right path component of the link-target to compare with. E.g. /sys/bus/usb/devices/usb7 points to ../../../devices/pci0000:00/0000:00:1d.7/usb7 . My plan is to check the bus name against the component before last and then extract the bus num from the last component's digit. Now again a question: Does this always work or is there probably another parent directory for usb7 in the global devices-directory? Thanks again... Regards, Carsten -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
