On Mon, 24 Jan 2011, Martin Mueller wrote: > Hi, > > we have a USB device with multiple configurations and need the second > configuration to be set without the first to be set before. As the > first configuration describes a class driver "generic.c" will switch > to it very early. Switching it to the second configuration through > unusual_devs.h or udev is too late and will take the device extra > time to switch from configuration 1->2. Is there a way to make USB > switch to configuration 2 other than changing usb/core/generic.c? To answer the original question: There is a way to do this. It's not easy and you probably won't want to use it. You have to know in advance which hub and which port the device will be plugged into. Then you have to have a userspace program which opens the hub device's usbfs file and issues a USBDEVFS_CLAIM_PORT ioctl for that port. When the device is plugged in, generic.c won't set any configuration; the user program can select a config by writing to /sys/bus/usb/devices/.../bConfigurationValue. Apart from this, there is no way to prevent generic.c from installing whichever config it chooses. However, if you're serious enough about this, you could add a new flag to include/linux/usb/quirks.h (something like USB_QUIRK_DONT_CONFIGURE) and put an entry for this device in drivers/usb/core/quirks.c. 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
